example of on_color method not working

movie_tests.py

from moviepy.editor import *
import gizeh

def make_redframe(t):
    '''Creates a red 1280x720 frame with hello world centered.  Background
    color is set to red.
    '''

    surface = gizeh.Surface(width=1280, height=720)
    rect = gizeh.rectangle(lx=1280, ly=720, xy=[1280/2,720/2], fill=(1,0,0))
    text = gizeh.text("hello world", fontfamily="Impact", fontsize=216,
                      fill=(1,1,1), xy=[1280/2,720/2])
    rect.draw(surface)
    text.draw(surface)
    return surface.get_npimage()

def make_frame(t):
    '''Creates 1280x720 from with hellow world not centered.  Background
    color not specified.
    '''

    surface = gizeh.Surface(width=1280, height=720)
    rect = gizeh.rectangle(lx=1280, ly=720, xy=[1280/2,720/2], fill=(0,0,1,0))
    text = gizeh.text("hello world", fontfamily="Impact", fontsize=216,
                      fill=(1,1,1), xy=[1280/2,720/2])
    rect.draw(surface)
    text.draw(surface)
    return surface.get_npimage()

def make_transparent_frame(t):
    '''Creates 1280x720 from with hellow world not centered.  Background
    color is blue but set to fully transparent
    '''

    surface = gizeh.Surface(width=1280, height=720)
    rect = gizeh.rectangle(lx=1280, ly=720, xy=[1280/2,720/2], fill=(0,0,1,0))
    text = gizeh.text("hello world", fontfamily="Impact", fontsize=216,
                      fill=(1,1,1), xy=[1280/2,720/2])
    rect.draw(surface)
    text.draw(surface)
    return surface.get_npimage()

if __name__ == '__main__':
    red_clip = VideoClip(make_redframe, duration=10)
    # Creates a 10s video with red background.
    red_clip.write_videofile("video_test_red.mp4", fps=24)

    green_clip_1 = VideoClip(make_frame, duration=10)
    green_clip_1 = green_clip_1.on_color(color=(0,1,0))
    # Expecting a 10s video with green background but the background is black
    green_clip_1.write_videofile("video_test_green_1.mp4", fps=24)

    green_clip_2 = VideoClip(make_transparent_frame, duration=10)
    green_clip_2 = green_clip_2.on_color(color=(0,1,0))
    # Expecting a 10s video with green background but the background is black
    green_clip_2.write_videofile("video_test_green_2.mp4", fps=24)