human
Solve the following python programming problem given the following code:
@ memoize 
def _build_extend(self, x_mapper, y_mapper, info, append) : 
    draw_line = _build_draw_line (append, x_mapper, x_mapper) 
    extend_line = _build_extend_line (draw_line) 
    x_name = self.x 
    y_name = self.y 
    def extend(aggs, df, vt, bounds, plot_start = True) : 
        xs = df [x_name].values 
        ys = df [y_name].values 
        cols = (aggs + info (df)) 
        extend_line (vt, bounds, xs, ys, plot_start, * cols) 
return extend 

    
    

    Fix the buggy line: draw_line = _build_draw_line (append, x_mapper, x_mapper)
assistant
#Here is Python program to fix the buggy line: draw_line = _build_draw_line (append, x_mapper, x_mapper)
.

draw_line = _build_draw_line (append, x_mapper, y_mapper)