code: def _replace_and_pad(fmt, marker, replacement):
      
      if marker not in fmt:
          return fmt
      if replacement:
          return fmt.replace(marker, replacement)
      # Remove mention of 'marker' in 'fmt', including leading space (if present)
      fmt = fmt.replace("%s " % marker, marker)
      return fmt.replace(marker, "")
docs: Args:
          fmt (str | unicode): Format to tweak
          marker (str | unicode): Marker to replace
          replacement (str | unicode): What to replace marker with
  
      Returns:
          (str): Resulting format, with marker replaced