human
Solve the following python programming problem given the following code:
@ cleanup 
def test_geom_hline_function() : 
    df = _build_line_df () 
    gg = ggplot (df, aes (x = 'wt', y = 'mpg')) 
    def ifunc(y) : 
        return np.mean (y) 
gg = ((gg + geom_point ()) + geom_hline (aes (y = 'mpg'), yintercept = df)) 
    assert_same_ggplot (gg, 'geom_hline_function') 

    
    

    Fix the buggy line: gg = ((gg + geom_point ()) + geom_hline (aes (y = 'mpg'), yintercept = df))
assistant
#Here is Python program to fix the buggy line: gg = ((gg + geom_point ()) + geom_hline (aes (y = 'mpg'), yintercept = df))
.

gg = ((gg + geom_point ()) + geom_hline (aes (y = 'mpg'), yintercept = def ifunc())