code: def save(self, segids, filepath=None, file_format='ply'):
      
      if type(segids) != list:
        segids = [segids]
  
      meshdata = self.get(segids)
  
      if not filepath:
        filepath = str(segids[0]) + "." + file_format
        if len(segids) > 1:
          filepath = "{}_{}.{}".format(segids[0], segids[-1], file_format)
  
      if file_format == 'obj':
        objdata = mesh_to_obj(meshdata, progress=self.vol.progress)
        objdata = '\n'.join(objdata) + '\n'
        data = objdata.encode('utf8')
      elif file_format == 'ply':
        data = mesh_to_ply(meshdata)
      else:
        raise NotImplementedError('Only .obj and .ply is currently supported.')
  
      with open(filepath, 'wb') as f:
        f.write(data)
docs: Save one or more segids into a common mesh format as a single file.
  
      segids: int, string, or list thereof
      filepath: string or None (optional)
      file_format: string (optional)
  
      Supported Formats: 'obj', 'ply'