human
I wrote the below code

    @_preprocess_data(replace_names=['x', 'y'], label_namer=None)
    def func_no_label(ax, x, y, ls='x', label=None, w='xyz'):
        return ('x:    %s,    y:    %s,    ls:    %s,    w:    %s,    label:    %s' % (list(x), list(y), ls, w, label))
    data = {'a': [1, 2], 'b': [8, 9], 'w': 'NOT'}
    assert (func_no_label(None, 'a', 'b', data=data) == 'x:    [1,    2],    y:    [8,    9],    ls:    x,    w:    xyz,    label:    None')
    assert (func_no_label(None, x='a', y='b', data=data) == 'x:    [1,    2],    y:    [8,    9],    ls:    x,    w:    xyz,    label:    None')
    assert (func_no_label(None, 'a', 'b', label='', data=data) == 'x:    [1,    2],    y:    [8,    9],    ls:    x,    w:    xyz,    label:    ')
    assert (func_no_label(None, 'a', 'b', label='text', data=data) == 'x:    [1,    2],    y:    [8,    9],    ls:    x,    w:    xyz,    label:    text')

What's a good function header?
assistant
#Here's a good function header.

def test_no_label_replacements():