code: def parse_float(float_str):
      
      factor = __get_factor(float_str)
      if factor != 1:
          float_str = float_str[:-1]
  
      try:
          return float(float_str.replace(',', '')) * factor
      except ValueError:
          return None
docs: Parse a string of the form 305.48b into a Python float.
         The terminal letter, if present, indicates e.g. billions.