code: def combine(self, members, output_file, dimension=None, start_index=None, stop_index=None, stride=None):
          
          nco = None
          try:
              nco = Nco()
          except BaseException:
              # This is not necessarily an import error (could be wrong PATH)
              raise ImportError("NCO not found.  The NCO python bindings are required to use 'Collection.combine'.")
  
          if len(members) > 0 and hasattr(members[0], 'path'):
              # A member DotDoct was passed in, we only need the paths
              members = [ m.path for m in members ]
  
          options  = ['-4']  # NetCDF4
          options += ['-L', '3']  # Level 3 compression
          options += ['-h']  # Don't append to the history global attribute
          if dimension is not None:
              if start_index is None:
                  start_index = 0
              if stop_index is None:
                  stop_index = ''
              if stride is None:
                  stride = 1
              options += ['-d', '{0},{1},{2},{3}'.format(dimension, start_index, stop_index, stride)]
          nco.ncrcat(input=members, output=output_file, options=options)
docs: Combine many files into a single file on disk.  Defaults to using the 'time' dimension.