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"""Callback Handler that prints to std out."""
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from typing import Any, Dict, List, Optional
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from langchain.callbacks.base import BaseCallbackHandler
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from langchain.input import print_text
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from langchain.schema import AgentAction, AgentFinish, LLMResult
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class StdOutCallbackHandler(BaseCallbackHandler):
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"""Callback Handler that prints to std out."""
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def on_llm_start(
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self, serialized: Dict[str, Any], prompts: List[str], **kwargs: Any
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) -> None:
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"""Print out the prompts."""
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pass
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def on_llm_end(self, response: LLMResult, **kwargs: Any) -> None:
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"""Do nothing."""
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pass
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def on_llm_error(self, error: Exception, **kwargs: Any) -> None:
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"""Do nothing."""
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pass
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def on_chain_start(
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self, serialized: Dict[str, Any], inputs: Dict[str, Any], **kwargs: Any
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) -> None:
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"""Print out that we are entering a chain."""
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class_name = serialized["name"]
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print(f"\n\n\033[1m> Entering new {class_name} chain...\033[0m")
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def on_chain_end(self, outputs: Dict[str, Any], **kwargs: Any) -> None:
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"""Print out that we finished a chain."""
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print("\n\033[1m> Finished chain.\033[0m")
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def on_chain_error(self, error: Exception, **kwargs: Any) -> None:
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"""Do nothing."""
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pass
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def on_tool_start(
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self,
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serialized: Dict[str, Any],
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action: AgentAction,
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color: Optional[str] = None,
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**kwargs: Any,
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) -> None:
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"""Print out the log in specified color."""
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print_text(action.log, color=color)
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def on_tool_end(
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self,
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output: str,
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color: Optional[str] = None,
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observation_prefix: Optional[str] = None,
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llm_prefix: Optional[str] = None,
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**kwargs: Any,
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) -> None:
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"""If not the final action, print out observation."""
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print_text(f"\n{observation_prefix}")
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print_text(output, color=color)
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print_text(f"\n{llm_prefix}")
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def on_tool_error(self, error: Exception, **kwargs: Any) -> None:
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"""Do nothing."""
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pass
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def on_text(
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self,
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text: str,
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color: Optional[str] = None,
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end: str = "",
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**kwargs: Optional[str],
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) -> None:
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"""Run when agent ends."""
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print_text(text, color=color, end=end)
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def on_agent_finish(
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self, finish: AgentFinish, color: Optional[str] = None, **kwargs: Any
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) -> None:
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"""Run on agent end."""
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print_text(finish.log, color=color, end="\n")
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