code: def write(self, data):
          
          m = self._convert_structure(data)
          self._file.write(self._format_mol(*m))
          self._file.write('M  END\n')
  
          for k, v in data.meta.items():
              self._file.write(f'>  <{k}>\n{v}\n')
          self._file.write('$$$$\n')
docs: write single molecule into file