Trouble Indexing with a Multi-index in Pandas : The following example from the docs works as expected:

    s = pd.Series([1, 2, 3, 4, 5, 6],index=pd.MultiIndex.from_product([["A", "B"], ["c", "d", "e"]]))

    s['A']

    c    1
    d    2
    e    3

However, for this example, from my data, such indexing raises an error:

    df = pd.DataFrame({'client_id': {('foo', '2018-01-29'): '1',
      ('bar', '2018-01-29'): '1',
      ('baz', '2018-01-29'): '1',
      ('alice', '2018-01-29'): '1',
      ('bob', '2018-01-29'): '1'}})

    df['alice']

    KeyError: 'alice'

What am I doing wrong?