def _to_litellm_role(role: Optional[str]) -> Literal["user", "assistant"]:
  """Converts a types.Content role to a litellm role.

  Args:
    role: The types.Content role.

  Returns:
    The litellm role.
  """

  if role in ["model", "assistant"]:
    return "assistant"
  return "user"
Converts a types.Content role to a litellm role.

  Args:
    role: The types.Content role.

  Returns:
    The litellm role.
  
src/google/adk/models/lite_llm.py