class_docstr: Creates a color picker for user to select a color as string input.
  Preprocessing: passes selected color value as a {str} into the function.
  Postprocessing: expects a {str} returned from function and sets color picker value to it.
  Examples-format: a {str} with a hexadecimal representation of a color, e.g. "#ff0000" for red.
  Demos: color_picker, color_generator
class_docstr_tok: ["Creates","a","color","picker","for","user","to","select","a","color","as","string","input",".","Preprocessing",":","passes","selected","color","value","as","a","{","str","}","into","the","function",".","Postprocessing",":","expects","a","{","str","}","returned","from","function","and","sets","color","picker","value","to","it",".","Examples-format",":","a","{","str","}","with","a","hexadecimal","representation","of","a","color",",","e.g",".","``","#","ff0000","''","for","red",".","Demos",":","color_picker",",","color_generator"]
code: def preprocess(self, payload: str | None) -> str | None:
      if payload is None:
          return None
      else:
          return str(payload)
  
file_path: gradio/gradio/components/color_picker.py
imports: from __future__ import annotations
  from typing import Any, Callable
  from gradio_client.documentation import document, set_documentation_group
  from gradio.components.base import Component
  from gradio.events import Events
label_desc: Use image node_id 4 for calling the ColorPicker obj's underlying member method code with example usage: obj.preprocess(payload) and returns: None, str