human
Solve the following python programming problem given the following code:
@ assert_no_logs 
def test_expand_background_position() : 
    'Test the ``background-position`` property.' 
    def position(css, * expected) : 
        [(name, [value])] = expand_to_dict (('background-position:' + css)).items () 
        assert (name == 'background_position') 
        assert (value == expected) 
for (css_x, val_x) in [('left', (0, '%')), ('center', (50, '%')), ('right', (100, '%')), ('4.5%', (4.5, '%')), ('12px', (12, 'px'))] : 
        for (css_y, val_y) in [('top', (0, '%')), ('center', (50, '%')), ('bottom', (100, '%')), ('7%', (7, '%')), ('1.5px', (1.5, 'px'))] : 
            position (('%s %s' % (css_x, css_y)), 'left', val_x, 'top', val_y) 
position (css_y, 'left', val_x, 'top', (50, '%')) 
position ('top', 'left', (50, '%'), 'top', (0, '%')) 
    position ('bottom', 'left', (50, '%'), 'top', (100, '%')) 
    position ('center top 10%', 'left', (50, '%'), 'top', (10, '%')) 
    position ('top 10% center', 'left', (50, '%'), 'top', (10, '%')) 
    position ('center bottom 10%', 'left', (50, '%'), 'bottom', (10, '%')) 
    position ('bottom 10% center', 'left', (50, '%'), 'bottom', (10, '%')) 
    position ('right top 10%', 'right', (0, '%'), 'top', (10, '%')) 
    position ('top 10% right', 'right', (0, '%'), 'top', (10, '%')) 
    position ('right bottom 10%', 'right', (0, '%'), 'bottom', (10, '%')) 
    position ('bottom 10% right', 'right', (0, '%'), 'bottom', (10, '%')) 
    position ('center left 10%', 'left', (10, '%'), 'top', (50, '%')) 
    position ('left 10% center', 'left', (10, '%'), 'top', (50, '%')) 
    position ('center right 10%', 'right', (10, '%'), 'top', (50, '%')) 
    position ('right 10% center', 'right', (10, '%'), 'top', (50, '%')) 
    position ('bottom left 10%', 'left', (10, '%'), 'bottom', (0, '%')) 
    position ('left 10% bottom', 'left', (10, '%'), 'bottom', (0, '%')) 
    position ('bottom right 10%', 'right', (10, '%'), 'bottom', (0, '%')) 
    position ('right 10% bottom', 'right', (10, '%'), 'bottom', (0, '%')) 
    position ('left 10% bottom 3px',...

    
    

    Fix the buggy line: position (css_y, 'left', val_x, 'top', (50, '%'))
assistant
#Here is Python code to fix the buggy line: position (css_y, 'left', val_x, 'top', (50, '%'))
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position (css_x, 'left', val_x, 'top', (50, '%'))