docs: def flatten_list(x: List[Any]) -> List[Any]:
      """
      Converts a list of lists into a flat list.
      
      Args:
          x: list of lists 
  
      Returns:
          flat list
          
      As per
      http://stackoverflow.com/questions/952914/making-a-flat-list-out-of-list-of-lists-in-python
  
      """  # noqa
      return [item for sublist in x for item in sublist]