code: def extent_string_to_array(extent_text):
      
      coordinates = extent_text.replace(' ', '').split(',')
      count = len(coordinates)
      if count != 4:
          message = (
              'Extent need exactly 4 value but got %s instead' % count)
          LOGGER.error(message)
          return None
  
      # parse the value to float type
      try:
          coordinates = [float(i) for i in coordinates]
      except ValueError as e:
          message = str(e)
          LOGGER.error(message)
          return None
      return coordinates
docs: Convert an extent string to an array.
  
      .. versionadded: 2.2.0
  
      :param extent_text: String representing an extent e.g.
          109.829170982, -8.13333290561, 111.005344795, -7.49226294379
      :type extent_text: str
  
      :returns: A list of floats, or None
      :rtype: list, None