code: def _mono_factor_getter(clip_duration):
      return lambda t, duration: np.minimum(
          1.0 * (clip_duration - t) / duration, 1
      )
  
imports: import numpy
  from moviepy.decorators import audio_video_fx, convert_parameter_to_seconds, requires_duration
label_desc: Use image node_id 1 for calling a global function with example usage: _mono_factor_getter(clip_duration) and returns: function