ffmpeg-python output gives file not found error

Question

I am trying out mpdecimate using ffmpeg-python library https://pypi.org/project/ffmpeg-python/.

However, I get a file not found error for the simple code below.

def remove_duplicate_ffmpeg(video_file_path,out_video_file_path):
    out, err = (
        ffmpeg
        .input(video_file_path)
        .filter('mpdecimate')
        .output(out_video_file_path)
        .run()
    )
    return out