human
Solve the following python programming problem given the following code:
def test_select_x() : 
    def _check(data, expected) : 
        v = api.Viz (data) 
        v.select_x () 
        assert (v.encoding.x.name == expected) 
data = dict (col1 = [1.0, 2.0, 3.0], col2 = ['A', 'B', 'C'], col3 = pd.date_range ('2012', periods = 3, freq = 'A'), col4 = pd.date_range ('2012', periods = 3, freq = 'A')) 
    _check (data, 'col3') 
    data = dict (col1 = [1.0, 2.0, 3.0], col2 = ['A', 'B', 'C'], col3 = ['A', 'B', 'C']) 
    _check (data, 'col2') 
    data = dict (col1 = [1.0, 2.0, 3.0], col2 = np.arange (3)) 
    _check (data, 'col1') 
    with pytest.raises (AssertionError) : 
        v = api.Viz (None) 
        v.select_x () 
with pytest.raises (AssertionError) : 
        v = api.Viz (dict ()) 
        v.select_x () 
data = dict (col1 = [1.0, 2.0, 3.0], col2 = ['A', 'B', 'C'], col3 = pd.date_range ('2012', periods = 3, freq = 'A'), col4 = pd.date_range ('2012', periods = 3, freq = 'A')) 
    v = api.Viz (data) 
    v.select_x (['N', 'T', 'Q', 'O']) 
    assert (data.encoding.x.name == 'col2') 

    
    

    Fix the buggy line: assert (data.encoding.x.name == 'col2')
assistant
#Here is Python program to fix the buggy line: assert (data.

assert (v.encoding.x.name == 'col2')