code: def iter(self, columnnames, order='', sort=True):
          
          from .tableiter import tableiter
          return tableiter(self, columnnames, order, sort)
docs: Return a tableiter object.
  
          :class:`tableiter` lets one iterate over a table by returning in each
          iteration step a reference table containing equal values for the given
          columns.
          By default a sort is done on the given columns to get the correct
          iteration order.
  
          `order`
            | 'ascending'  is iterate in ascending order (is the default).
            | 'descending' is iterate in descending order.
          `sort=False`
            do not sort (because table is already in correct order).
  
          For example, iterate by time through a measurementset table::
  
            t = table('3c343.MS')
            for ts in t.iter('TIME'):
              print ts.nrows()