def blink(clip, d_on, d_off):
 newclip = copy(clip)
 if (newclip.mask is None):
  newclip = newclip.with_mask()
 D = (d_on + d_off)
 newclip.mask = newclip.mask.fl((lambda gf, t: (gf(t) * ((t % D) < d_on))))
 return newclip

def blink ( clip , d_on , d_off ) : newclip = copy ( clip ) if ( newclip . mask is None ) : newclip = newclip . with_mask ( ) D = ( d_on + d_off ) newclip . mask = newclip . mask . fl ( ( lambda gf , t : ( gf ( t ) * ( ( t % D ) < d_on ) ) ) ) return newclip
makes the clip blink .