code: def read_meta_line(self, f):
          
          line = f.readline()
          if isinstance(line, bytes):
              line = line.decode('utf-8-sig')
          name, value = '', ''
          if line.isspace():
              return (name, value)
          if line.find('=') > 0:
              name, value = line.split('=', 1)
              name = name.rstrip().lower()
              value = value.strip()
          name = '' if any([c.isspace() for c in name]) else name
          if not name:
              raise ParsingError("Invalid file header line")
          return (name, value)
docs: Read one line from a file format header and return a (name, value)
          tuple, where name is lowercased. Returns ('', '') if the next line is
          blank. Raises ParsingError if next line in f is not a valid header
          line.