def METHOD_NAME():
    assert utils.select_x(None) is None
    def _check(d, expected):
        x = utils.select_x(d)
        assert x == expected
    data = dict(
        col1=[1.0, 2.0, 3.0],  # Q
        col2=["A", "B", "C"],  # N
        col3=pd.date_range("2012", periods=3, freq="A"),
    )  # T
    _check(data, "col3")
    data = dict(col1=[1.0, 2.0, 3.0], col2=["A", "B", "C"])  # Q  # N
    _check(data, "col2")
    data = dict(col1=[1.0, 2.0, 3.0])  # Q
    _check(data, "col1")
    # Custom order
    data = dict(
        col1=[1.0, 2.0, 3.0],  # Q
        col2=["A", "B", "C"],  # N
        col3=pd.date_range("2012", periods=3, freq="A"),  # T
        col4=pd.date_range("2012", periods=3, freq="A"),
    )  # T
    selected_x = utils.select_x(data, ["N", "T", "Q", "O"])
    assert selected_x == "col2"
    # Len < 1
    assert utils.select_x(dict()) is None