code: def export(self, filename, file_format=None, type=None, typequote='"'):
          
          exporter = self._get_exporter(filename, file_format=file_format)
          exporter(filename, type=type, typequote=typequote)
docs: export density to file using the given format.
  
          The format can also be deduced from the suffix of the filename
          though the *format* keyword takes precedence.
  
          The default format for export() is 'dx'.  Use 'dx' for
          visualization.
  
          Implemented formats:
  
          dx
              :mod:`OpenDX`
          pickle
              pickle (use :meth:`Grid.load` to restore); :meth:`Grid.save`
              is simpler than ``export(format='python')``.
  
          Parameters
          ----------
  
          filename : str
              name of the output file
  
          file_format : {'dx', 'pickle', None} (optional)
              output file format, the default is "dx"
  
          type : str (optional)
              for DX, set the output DX array type, e.g., "double" or "float".
              By default (``None``), the DX type is determined from the numpy
              dtype of the array of the grid (and this will typically result in
              "double").
  
              .. versionadded:: 0.4.0
  
          typequote : str (optional)
              For DX, set the character used to quote the type string;
              by default this is a double-quote character, '"'.
              Custom parsers like the one from NAMD-GridForces (backend for MDFF)
              expect no quotes, and typequote='' may be used to appease them.
  
              .. versionadded:: 0.5.0