code: def _to_snake_case(string):
          
          sub_string = r'\1_\2'
          string = REGEX_CAMEL_FIRST.sub(sub_string, string)
          return REGEX_CAMEL_SECOND.sub(sub_string, string).lower()
docs: Return a snake cased version of the input string.
  
          Args:
              string (str): A camel cased string.
  
          Returns:
              str: A snake cased string.