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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def iter(self, columnnames, order='', sort=True):
 """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() """

        from .tableiter import tableiter
        return tableiter(self, columnnames, order, sort)