Sets table, with column headers and separators.

def _SetTable(self, table):
    """Sets table, with column headers and separators."""
    if not isinstance(table, TextTable):
      raise TypeError('Not an instance of TextTable.')
    self.Reset()
    self._table = copy.deepcopy(table._table)   # pylint: disable=W0212
    # Point parent table of each row back ourselves.
    for row in self:
      row.table = self