RunnablePassthrough<RunInput extends Object> class

A RunnablePassthrough takes the input it receives and passes it through as output.

You can create a RunnablePassthrough using the Runnable.passthrough static method.

When you call invoke on a RunnablePassthrough, it will return the input it receives.

Example:

final openaiApiKey = Platform.environment['OPENAI_API_KEY'];
final model = ChatOpenAI(apiKey: openaiApiKey);

final promptTemplate = ChatPromptTemplate.fromTemplate(
  'Tell me a joke about {foo}',
);

final map = Runnable.fromMap({
  'foo': Runnable.passthrough(),
});
final chain = map | promptTemplate | model | StringOutputParser();

final res = await chain.invoke('bears');
print(res);
// Why don't bears wear shoes? Because they have bear feet!