'Access TableColumns by name and show that item access returns
a Column that refers to underlying table data'

def test_by_name(self, table_data):

    self.t = table_data.Table(table_data.COLS)
    self.tc = self.t.columns
    assert (self.tc['a'].name == 'a')
    assert (self.tc['a'][1] == 2)
    assert (self.tc['a'].description == 'da')
    assert (self.tc['a'].format == 'fa')
    assert (self.tc['a'].meta == {'ma': 1})
    assert (self.tc['a'].unit == 'ua')
    assert self.tc['a'].attrs_equal(table_data.COLS[0])
    assert isinstance(self.tc['a'], table_data.Column)
    self.tc['b'][1] = 0
    assert (self.t['b'][1] == 0)
