code: def _handle_divider_color(divider):
      if divider is True:
          return "auto"
      valid_colors = [
          "blue",
          "green",
          "orange",
          "red",
          "violet",
          "gray",
          "grey",
          "rainbow",
      ]
      if divider in valid_colors:
          return divider
      else:
          raise StreamlitAPIException(
              f"Divider parameter has invalid value: `{divider}`. Please choose from: {', '.join(valid_colors)}."
          )
  
file_path: streamlit/lib/streamlit/elements/heading.py
imports: from enum import Enum
  from typing import TYPE_CHECKING, Optional, Union, cast
  from typing_extensions import Literal
  from streamlit.errors import StreamlitAPIException
  from streamlit.proto.Heading_pb2 import Heading
  from streamlit.runtime.metrics_util import gather_metrics
  from streamlit.string_util import clean_text
  from streamlit.type_util import SupportsStr
label_desc: Use image node_id 5 for calling the HeadingMixin obj's underlying member method code with example usage: obj._handle_divider_color(divider) and returns: str, divider