def METHOD_NAME():
    mkey = cirq.MeasurementKey('key')
    mkey2 = cirq.with_key_path(mkey, ('a',))
    assert mkey2.name == mkey.name
    assert mkey2.path == ('a',)
    assert mkey2 == mkey.with_key_path_prefix('a')
    mkey3 = mkey2.with_key_path_prefix('b')
    assert mkey3.name == mkey.name
    assert mkey3.path == ('b', 'a')