code: def parse_radl(data):
      
  
      if data is None:
          return None
      elif os.path.isfile(data):
          f = open(data)
          data = "".join(f.readlines())
          f.close()
      elif data.strip() == "":
          return RADL()
      data = data + "\n"
  
      parser = RADLParser(lextab='radl')
      return parser.parse(data)
docs: Parse a RADL document.
  
      Args:
      - data(str): filepath to a RADL content or a string with content.
  
      Return: RADL object.