diff --git a/doc/libmodal-lua.txt b/doc/libmodal-lua.txt
index 778a0c4..42d3b55 100644
--- a/doc/libmodal-lua.txt
+++ b/doc/libmodal-lua.txt
@@ -60,6 +60,46 @@ MODULES                                                 *libmodal-lua-modules*
 │   └──   `.WindowState`
 └──   `.Vars`
 
+==============================================================================
+2. `libmodal.classes`                                     *libmodal-lua-classes*
+
+`libmodal.classes` is a small library to help shorten the amount of
+boilerplate code that it takes to set up a `metatable` and subsequent
+subtables.
+
+There aren't an astounding amount of functions: the intent is not to implement
+object orientation into Lua, rather it is to help facilitate the emulation of
+object orientation through `metatable`s.
+
+------------------------------------------------------------------------------
+FUNCTIONS                                     *libmodal-lua-classes-functions*
+
+`classes`.new({name}, {base})                       *libmodal-lua-classes.new()*
+
+	Define a class-metatable.
+
+	Parameters: ~
+		{name}  The name of the class.
+
+			Note: this value is used for `classes.type()`.
+
+		{base}  Optional. The base class to use.
+
+	Return: ~
+		A table set up to for use as a `metatable`.
+
+`classes`.type({value})                            *libmodal-lua-classes.type()*
+
+	Get the type of some {value}.
+
+	Parameters: ~
+		{value}  The value to get the type of.
+
+	Return: ~
+		* If {value} is a `table` and it has a `__type` attribute, return
+		  `__type`.
+		* Else, return `type(`{value}`)`
+
 ==============================================================================
 3. `libmodal.collections`                             *libmodal-lua-collections*
 
@@ -586,6 +626,8 @@ FUNCTIONS                                         *libmodal-lua-Layer-functions*
 
 	Note: mappings only get replaced for the current buffer.
 
+	*Error	when the Layer has been entered previously but hasn't been exited.
+
 	Example: ~
 >
 		local libmodal = require('libmodal')
@@ -692,6 +734,8 @@ FUNCTIONS                                         *libmodal-lua-Layer-functions*
 
 	Exit the `Layer`.
 
+	*Error	when the Layer has not been entered yet.
+
 	Example: ~
 >
 		local libmodal = require('libmodal')
@@ -900,6 +944,34 @@ opened with the following options: >
 	}
 <
 
+------------------------------------------------------------------------------
+VARIABLES                                       *libmodal-lua-Popup-variables*
+
+`Popup`.config                                   *libmodal-lua-Popup.apiOptions*
+
+	The options used when opening a `Popup`.
+
+	Note: this can be overwritten to change the default behavior of `Popup`.
+
+	Type: ~
+		|nvim_open_win| {config} `table`.
+
+	Value: ~
+>
+	{
+		['anchor']    = 'SW',
+		['col']       = api.nvim_get_option('columns') - 1,
+		['focusable'] = false,
+		['height']    = 1,
+		['relative']  = 'editor',
+		['row']       = api.nvim_get_option('lines')
+		                - api.nvim_get_option('cmdheight')
+		                - 1,
+		['style']     = 'minimal',
+		['width']     = 25
+	}
+<
+
 ------------------------------------------------------------------------------
 FUNCTIONS                                       *libmodal-lua-Popup-functions*
 
diff --git a/examples/key-combos.vim b/examples/key-combos.vim
index b89ba8d..3009d43 100644
--- a/examples/key-combos.vim
+++ b/examples/key-combos.vim
@@ -1,7 +1,7 @@
 let s:barModeCombos = {
 \	'zf': 'split',
 \	'zfo': 'vsplit',
-\	'zfc': 'tabnew'
+\	'zfc': 'q'
 \}
 
 call libmodal#Enter('BAR', s:barModeCombos)
diff --git a/examples/lua/layer-simple.lua b/examples/lua/layer-simple.lua
index a4ba12d..eadb696 100644
--- a/examples/lua/layer-simple.lua
+++ b/examples/lua/layer-simple.lua
@@ -14,6 +14,7 @@ local exitFunc = libmodal.layer.enter('FOO', {
 	}
 })
 
+-- the layer will deactivate in 5 seconds.
 vim.loop.new_timer():start(5000, 0, vim.schedule_wrap(
 	function() exitFunc(); print('EXITED.') end
 ))
diff --git a/lua/libmodal/init.lua b/lua/libmodal/init.lua
index faad8ed..c4834e8 100644
--- a/lua/libmodal/init.lua
+++ b/lua/libmodal/init.lua
@@ -4,7 +4,7 @@
 	 */
 --]]
 
-local libmodal  = require('libmodal/src')
+local libmodal = require('libmodal/src')
 
 --[[
 	/*
diff --git a/lua/libmodal/src/Indicator/init.lua b/lua/libmodal/src/Indicator/init.lua
index 29cd618..cabde39 100644
--- a/lua/libmodal/src/Indicator/init.lua
+++ b/lua/libmodal/src/Indicator/init.lua
@@ -4,9 +4,9 @@
 	 */
 --]]
 
-local Indicator = {}
-
-Indicator.HighlightSegment = require('libmodal/src/Indicator/HighlightSegment')
+local Indicator = {
+	['HighlightSegment'] = require('libmodal/src/Indicator/HighlightSegment')
+}
 
 -- highlight group names
 local _HL_GROUP_MODE    = 'LibmodalPrompt'
diff --git a/lua/libmodal/src/Layer.lua b/lua/libmodal/src/Layer.lua
index 3aaaf19..d9c5f54 100644
--- a/lua/libmodal/src/Layer.lua
+++ b/lua/libmodal/src/Layer.lua
@@ -47,6 +47,10 @@ local _metaLayer = require('libmodal/src/classes').new(Layer.TYPE)
 ]]
 ---------------------------
 function _metaLayer:enter()
+	if self._priorKeymap then
+		error('This layer has already been entered.')
+	end
+
 	-- add local aliases.
 	local layerKeymap = self._keymap
 	local priorKeymap = {}
@@ -203,6 +207,10 @@ end
 ]]
 --------------------------
 function _metaLayer:exit()
+	if not self._priorKeymap then
+		error('This layer has not been entered yet.')
+	end
+
 	for mode, mappings in pairs(self._keymap) do
 		for lhs, _ in pairs(mappings) do
 			self:_unmapFromBuffer(mode, lhs)
diff --git a/lua/libmodal/src/Mode/init.lua b/lua/libmodal/src/Mode.lua
similarity index 90%
rename from lua/libmodal/src/Mode/init.lua
rename to lua/libmodal/src/Mode.lua
index 4f52bce..05e29ae 100644
--- a/lua/libmodal/src/Mode/init.lua
+++ b/lua/libmodal/src/Mode.lua
@@ -4,13 +4,15 @@
 	 */
 --]]
 
-local classes     = require('libmodal/src/classes')
-local globals     = require('libmodal/src/globals')
-local collections = require('libmodal/src/collections')
-local utils       = require('libmodal/src/utils')
-local Vars        = require('libmodal/src/Vars')
+local classes    = require('libmodal/src/classes')
+local globals    = require('libmodal/src/globals')
+local ParseTable = require('libmodal/src/collections/ParseTable')
+local utils      = require('libmodal/src/utils')
+local Vars       = require('libmodal/src/Vars')
 
-local api  = utils.api
+local api        = utils.api
+
+local collections = nil
 
 --[[
 	/*
@@ -18,10 +20,7 @@ local api  = utils.api
 	 */
 --]]
 
-local Mode = {
-	['Popup'] = require('libmodal/src/Mode/Popup'),
-	['TYPE']  = 'libmodal-mode'
-}
+local Mode = {['TYPE']  = 'libmodal-mode'}
 
 local _HELP = '?'
 local _TIMEOUT = {
@@ -90,8 +89,8 @@ function _metaMode:_checkInputForMapping()
 				-- Send input to interrupt a blocking `getchar`
 				_TIMEOUT:SEND()
 				-- if there is a command, execute it.
-				if cmd[collections.ParseTable.CR] then
-					api.nvim_command(cmd[collections.ParseTable.CR])
+				if cmd[ParseTable.CR] then
+					api.nvim_command(cmd[ParseTable.CR])
 				end
 				-- clear input
 				inputBytes:clear()
@@ -117,7 +116,7 @@ function _metaMode:enter()
 	-- intialize variables that are needed for each recurse of a function
 	if type(self._instruction) == globals.TYPE_TBL then
 		-- Initialize the input history variable.
-		self._popups:push(Mode.Popup.new())
+		self._popups:push(require('libmodal/src/collections/Popup').new())
 	end
 
 
@@ -156,10 +155,10 @@ function _metaMode:_initMappings()
 	self.inputBytes = setmetatable({}, _metaInputBytes)
 
 	-- Build the parse tree.
-	self.mappings = collections.ParseTable.new(self._instruction)
+	self.mappings = ParseTable.new(self._instruction)
 
 	-- Create a table for mode-specific data.
-	self._popups = collections.Stack.new()
+	self._popups = require('libmodal/src/collections/Stack').new()
 
 	-- Create a variable for whether or not timeouts are enabled.
 	self._timeouts = Vars.new('timeouts', self._name)
diff --git a/lua/libmodal/src/ModeLayer.lua b/lua/libmodal/src/ModeLayer.lua
deleted file mode 100644
index 2676dca..0000000
--- a/lua/libmodal/src/ModeLayer.lua
+++ /dev/null
@@ -1,127 +0,0 @@
---[[
-	/*
-	 * MODULE
-	 */
---]]
-
-local ModeLayer = {['TYPE'] = 'libmodal-mode-layer'}
-
---[[
-	/*
-	 * META `ModeLayer`
-	 */
---]]
-
-local _metaModeLayer = require('libmodal/src/classes').new(ModeLayer.TYPE)
-
-function _metaModeLayer:map(keys, mapping)
-	local priorInstruction = self._priorInstruction
-	local layerInstruction = self._instruction
-
-	if priorInstruction then
-		local modeInstruction = self._mode._instruction
-
-		-- only save the value from `mode` when adding a new mapping.
-		if not layerInstruction[keys] then
-			priorInstruction[keys] = modeInstruction:parseGet(keys)
-		end
-
-		-- map the keys to mode.
-		modeInstruction:parsePut(keys, mapping)
-	end
-
-	-- add the keys to the instruction.
-	layerInstruction[keys] = mapping
-end
-
-function _metaModeLayer:unmap(keys)
-	local priorInstruction = self._priorInstruction or {}
-	local layerInstruction = self._instruction
-
-	if priorInstruction[keys] then
-		self._mode._instruction:parsePut(keys, priorInstruction[keys])
-		priorInstruction[keys] = nil
-	end
-
-	-- remove `keys` from the instruction.
-	layerInstruction[keys] = nil
-end
-
-
--------------------------------
---[[ SUMMARY:
-	* Enter the `ModeLayer`, replacing any conflicting mappings.
-]]
--------------------------------
-function _metaModeLayer:enter()
-	-- Create aliases.
-	local layerMode        = self._mode
-	local layerInstruction = self._instruction
-
-	-- Create a new `priorInstruction`.
-	local priorInstruction = nil
-
-	if self._isTable then -- the layer is a table
-		local modeInstruction = mode._instruction
-		priorInstruction = {}
-
-		for keys, mapping in pairs(layerInstruction) do
-			priorInstruction[keys] = modeInstruction:parseGet(keys)
-			modeInstruction:parsePut(keys, mapping)
-		end
-	else -- the layer is a function
-		priorInstruction  = layerMode._instruction
-		mode._instruction = layerInstruction
-	end
-
-	self._priorInstruction = priorInstruction
-end
-
--------------------------------
---[[ SUMMARY:
-	* Exit the `ModeLayer`, and restore any overwritten mappings.
-]]
--------------------------------
-function _metaModeLayer:exit()
-	if self._isTable then
-		local modeInstruction  = self._mode._instruction
-
-		for keys, mapping in pairs(self._priorInstruction) do
-			modeInstruction:parsePut(keys, mapping)
-		end
-	else
-		self._mode._instruction = self._priorInstruction
-	end
-
-	self._priorInstruction = nil
-end
-
---[[
-	/*
-	 * CLASS `ModeLayer`
-	 */
---]]
-
------------------------------------------
---[[ SUMMARY:
-	* Create a new `ModeLayer`.
-]]
------------------------------------------
-function ModeLayer.new(mode, instruction)
-	if require('libmodal/src/classes').type(mode) == require('libmodal/src/Mode').TYPE
-		and type(mode._instruction) == type(instruction)
-	then
-		return setmetatable(
-			{
-				['_isTable'] = type(instruction) == require('libmodal/src/globals').TYPE_TBL,
-				['_instruction'] = instruction,
-				['_mode']        = mode
-			}, _metaModeLayer
-		)
-	else
-		error('Either `mode` is not a `Mode`, '
-			.. 'or `instruction` is not the same type '
-			.. 'as it was when `mode` was created.'
-		)
-	end
-end
diff --git a/lua/libmodal/src/PromptLayer.lua b/lua/libmodal/src/PromptLayer.lua
deleted file mode 100644
index fdd68dc..0000000
--- a/lua/libmodal/src/PromptLayer.lua
+++ /dev/null
@@ -1,101 +0,0 @@
---[[
-	/*
-	 * IMPORTS
-	 */
---]]
-
-local classes = require('libmodal/src/classes')
-
---[[
-	/*
-	 * MODULE
-	 */
---]]
-
-local PromptLayer = {['TYPE'] = 'libmodal-prompt-layer'}
-
---[[
-	/*
-	 * META `PromptLayer`
-	 */
---]]
-
-local _metaPromptLayer = classes.new(PromptLayer.TYPE)
-
--------------------------------
---[[ SUMMARY:
-	* Enter the `PromptLayer`, replacing any conflicting executes.
-]]
--------------------------------
-function _metaPromptLayer:enter()
-	-- Create aliases.
-	local layerPrompt      = self._prompt
-	local layerInstruction = self._instruction
-
-	-- Create a new `priorInstruction`.
-	local priorInstruction = nil
-
-	if self._isTable then -- the layer is a table
-		local promptInstruction = prompt._instruction
-		priorInstruction = {}
-
-		for command, execute in pairs(layerInstruction) do
-			priorInstruction[command] = promptInstruction[command]
-			promptInstruction[command]  = execute
-		end
-	else -- the layer is a function
-		priorInstruction  = layerPrompt._instruction
-		prompt._instruction = layerInstruction
-	end
-
-	self._priorInstruction = priorInstruction
-end
-
--------------------------------
---[[ SUMMARY:
-	* Exit the `PromptLayer`, and restore any overwritten executes.
-]]
--------------------------------
-function _metaPromptLayer:exit()
-	if self._isTable then
-		local promptInstruction  = self._prompt._instruction
-
-		for command, execute in pairs(self._priorInstruction) do
-			promptInstruction[command] = execute
-		end
-	else
-		self._prompt._instruction = self._priorInstruction
-	end
-
-	self._priorInstruction = nil
-end
-
---[[
-	/*
-	 * CLASS `PromptLayer`
-	 */
---]]
-
------------------------------------------
---[[ SUMMARY:
-	* Create a new `PromptLayer`.
-]]
------------------------------------------
-function PromptLayer.new(prompt, instruction)
-	if classes.type(prompt) == require('libmodal/src/Prompt').TYPE
-		and type(prompt._instruction) == type(instruction)
-	then
-		return setmetatable(
-			{
-				['_isTable'] = type(instruction) == require('libmodal/src/globals').TYPE_TBL,
-				['_instruction'] = instruction,
-				['_prompt']        = prompt
-			}, _metaPromptLayer
-		)
-	else
-		error('Either `prompt` is not a `Prompt`, '
-			.. 'or `instruction` is not the same type '
-			.. 'as it was when `prompt` was created.'
-		)
-	end
-end
diff --git a/lua/libmodal/src/classes.lua b/lua/libmodal/src/classes.lua
index 63de69b..c5ede09 100644
--- a/lua/libmodal/src/classes.lua
+++ b/lua/libmodal/src/classes.lua
@@ -1,44 +1,37 @@
---[[
-	/*
-	 * MODULE
-	 */
---]]
-
-local classes = {}
-
---------------------------
---[[ SUMMARY:
-	* Define a class-metatable.
-]]
---[[
-	* `name` => the name of the class.
-	* `base` => the base class to use (`{}` by default).
-]]
---------------------------------
-function classes.new(name, ...)
-	-- set self to `base`, or `{}` if nil.
-	local self = unpack({...}) or {}
-
-	-- set `__index`.
-	if not self.__index then
-		self.__index = self
+return {
+	-------------------------
+	--[[ SUMMARY:
+		* Define a class-metatable.
+	]]
+	--[[
+		* `name` => the name of the class.
+		* `base` => the base class to use (`{}` by default).
+	]]
+	-------------------------
+	new = function(name, ...)
+		-- set self to `base`, or `{}` if nil.
+		local self = unpack({...}) or {}
+
+		-- set `__index`.
+		if not self.__index then
+			self.__index = self
+		end
+
+		-- set `__type`.
+		self.__type  = name
+
+		return self
+	end,
+
+	------------------
+	--[[ SUMMARY:
+		* Get the type of some value `v`, if it has one.
+	]]
+	--[[ PARAMS:
+		* `v` => the value to get the type of.
+	]]
+	------------------
+	type = function(v)
+		return v.__type or type(v)
 	end
-
-	-- set `__type`.
-	self.__type  = name
-
-	return self
-end
-
-------------------------
-function classes.type(v)
-	return v.__type or type(v)
-end
-
---[[
-	/*
-	 * PUBLICIZE `classes`
-	 */
---]]
-
-return classes
+}
diff --git a/lua/libmodal/src/Mode/Popup.lua b/lua/libmodal/src/collections/Popup.lua
similarity index 76%
rename from lua/libmodal/src/Mode/Popup.lua
rename to lua/libmodal/src/collections/Popup.lua
index 5035b2a..013e964 100644
--- a/lua/libmodal/src/Mode/Popup.lua
+++ b/lua/libmodal/src/collections/Popup.lua
@@ -12,19 +12,20 @@ local api = vim.api
 	 */
 --]]
 
-local Popup = {['TYPE'] = 'libmodal-popup'}
-
-local _winOpenOpts = {
-	['anchor']    = 'SW',
-	['col']       = api.nvim_get_option('columns') - 1,
-	['focusable'] = false,
-	['height']    = 1,
-	['relative']  = 'editor',
-	['row']       = api.nvim_get_option('lines')
-	                - api.nvim_get_option('cmdheight')
-	                - 1,
-	['style']     = 'minimal',
-	['width']     = 25,
+local Popup = {
+	['TYPE'] = 'libmodal-popup',
+	['config'] = {
+		['anchor']    = 'SW',
+		['col']       = api.nvim_get_option('columns') - 1,
+		['focusable'] = false,
+		['height']    = 1,
+		['relative']  = 'editor',
+		['row']       = api.nvim_get_option('lines')
+		                - api.nvim_get_option('cmdheight')
+		                - 1,
+		['style']     = 'minimal',
+		['width']     = 25
+	}
 }
 
 --[[
@@ -85,13 +86,14 @@ end
 
 function Popup.new()
 	local buf = api.nvim_create_buf(false, true)
+	local Popup = require('libmodal/src/Mode/Popup')
 
 	return setmetatable(
 		{
 			['_buffer']     = buf,
 			['_inputChars'] = {},
 			['_window']      = api.nvim_call_function(
-				'nvim_open_win', {buf, false, _winOpenOpts}
+				'nvim_open_win', {buf, false, Popup.config}
 			)
 		},
 		_metaPopup
diff --git a/lua/libmodal/src/collections/init.lua b/lua/libmodal/src/collections/init.lua
index 74b82ba..b446561 100644
--- a/lua/libmodal/src/collections/init.lua
+++ b/lua/libmodal/src/collections/init.lua
@@ -1,6 +1,5 @@
-local collections = {}
-
-collections.ParseTable = require('libmodal/src/collections/ParseTable')
-collections.Stack      = require('libmodal/src/collections/Stack')
-
-return collections
+return {
+	['ParseTable'] = require('libmodal/src/collections/ParseTable'),
+	['Popup']      = require('libmodal/src/collections/Popup'),
+	['Stack']      = require('libmodal/src/collections/Stack')
+}
diff --git a/lua/libmodal/src/globals.lua b/lua/libmodal/src/globals.lua
index fedcacb..4254675 100644
--- a/lua/libmodal/src/globals.lua
+++ b/lua/libmodal/src/globals.lua
@@ -1,41 +1,25 @@
---[[
-	/*
-	 * MODULE
-	 */
---]]
+local _VIM_FALSE = 0
+local _VIM_TRUE  = 1
 
-local globals = {}
+return {
+	['DEFAULT_ERROR_TITLE'] = 'vim-libmodal error',
 
---[[
-	/*
-	 * TABLE `globals`
-	 */
---]]
+	['ESC_NR'] = 27,
 
-globals.DEFAULT_ERROR_TITLE = 'vim-libmodal error'
+	['TYPE_FUNC'] = 'function',
+	['TYPE_NUM']  = 'number',
+	['TYPE_STR'] = 'string',
+	['TYPE_TBL'] = 'table',
 
-globals.ESC_NR = 27
+	['VIM_FALSE'] = _VIM_FALSE,
+	['VIM_TRUE']  = _VIM_TRUE,
 
-globals.TYPE_FUNC = 'function'
-globals.TYPE_NUM  = 'number'
-globals.TYPE_STR = 'string'
-globals.TYPE_TBL = 'table'
+	is_false = function(val)
+		return val == false or val == _VIM_FALSE
+	end,
 
-globals.VIM_FALSE = 0
-globals.VIM_TRUE  = 1
+	is_true = function(val)
+		return val == true  or val == _VIM_TRUE
+	end
+}
 
-function globals.is_false(val)
-	return val == false or val == globals.VIM_FALSE
-end
-
-function globals.is_true(val)
-	return val == true or val == globals.VIM_TRUE
-end
-
---[[
-	/*
-	 * PUBLICIZE MODULE
-	 */
---]]
-
-return globals
diff --git a/lua/libmodal/src/init.lua b/lua/libmodal/src/init.lua
index ac3f0ab..ac122a2 100644
--- a/lua/libmodal/src/init.lua
+++ b/lua/libmodal/src/init.lua
@@ -1,24 +1,10 @@
---[[
-	/*
-	 * MODULE
-	 */
---]]
-
-local libmodal = {}
-
-libmodal.classes     = require('libmodal/src/classes')
-libmodal.collections = require('libmodal/src/collections')
-libmodal.globals     = require('libmodal/src/globals')
-libmodal.Indicator   = require('libmodal/src/Indicator')
-libmodal.Layer       = require('libmodal/src/Layer')
-libmodal.Mode        = require('libmodal/src/Mode')
-libmodal.Prompt      = require('libmodal/src/Prompt')
-libmodal.utils       = require('libmodal/src/utils')
-
---[[
-	/*
-	 * PUBLICIZE MODULE
-	 */
---]]
-
-return libmodal
+return {
+	['classes']     = require('libmodal/src/classes'),
+	['collections'] = require('libmodal/src/collections'),
+	['globals']     = require('libmodal/src/globals'),
+	['Indicator']   = require('libmodal/src/Indicator'),
+	['Layer']       = require('libmodal/src/Layer'),
+	['Mode']        = require('libmodal/src/Mode'),
+	['Prompt']      = require('libmodal/src/Prompt'),
+	['utils']       = require('libmodal/src/utils')
+}
diff --git a/lua/libmodal/src/utils/init.lua b/lua/libmodal/src/utils/init.lua
index 07076d7..dc344a2 100644
--- a/lua/libmodal/src/utils/init.lua
+++ b/lua/libmodal/src/utils/init.lua
@@ -24,8 +24,11 @@ utils.WindowState = require('libmodal/src/utils/WindowState')
 ]]
 ----------------------------------
 function utils.show_error(pcall_err)
-	utils.api.nvim_bell()
-	utils.api.nvim_show_err(
+	local api = utils.api
+
+	api.nvim_bell()
+
+	api.nvim_show_err(
 		require('libmodal/src/globals').DEFAULT_ERROR_TITLE,
 		api.nvim_get_vvar('throwpoint')
 		.. '\n' ..