prompt nit (#141)

doing some cleanup, and i think this just simplifies things...

langchain/prompts/prompt.py

@@ -94,8 +94,7 @@ class Prompt(BaseModel, BasePrompt):
         Returns:
             The final prompt generated.
         """
-        example_str = example_separator.join(examples)
-        template = prefix + example_str + suffix
+        template = example_separator.join([prefix, *examples, suffix])
         return cls(input_variables=input_variables, template=template)
 
     @classmethod

tests/unit_tests/test_prompt.py

@@ -51,8 +51,8 @@ Question: {question}
 Answer:"""
     input_variables = ["question"]
     example_separator = "\n\n"
-    prefix = """Test Prompt:\n\n"""
-    suffix = """\n\nQuestion: {question}\nAnswer:"""
+    prefix = """Test Prompt:"""
+    suffix = """Question: {question}\nAnswer:"""
     examples = [
         """Question: who are you?\nAnswer: foo""",
         """Question: what are you?\nAnswer: bar""",