docs: def _parse(self):
          """read in a file and return a MOPFile object."""
          with open(self.filename, 'r') as fobj:
              lines = fobj.read().split('\n')
  
          # Create a header object with content at start of file
          self.header = MOPHeader(self.subfmt).parser(lines)
  
          # Create a data attribute to hold an astropy.table.Table object
          self.data = MOPDataParser(self.header).parse(lines)