cycle filler

tmin = cmds.playbackOptions(q=1,min=1)
tmax = cmds.playbackOptions(q=1,max=1)

namespaces = list(set([i.split(':')[0] for i in cmds.ls(sl=1) if ':' in i]))


_ctrl_ = 'nurbsCircle1'

infinity_type = cmds.setInfinity(_ctrl_,attribute='t',q=1,poi=1)[0]

first_key = cmds.keyframe(_ctrl_,attribute='tx',q=1)[0]
last_key = cmds.keyframe(_ctrl_,attribute='tx',q=1)[-1]
cycle_length = last_key-first_key


cmds.copyKey(_ctrl_,t=(first_key,last_key))

paste_position = last_key
while paste_position + cycle_length <= tmax + cycle_length:
    cmds.pasteKey(_ctrl_,t=(paste_position,paste_position))
    paste_position += cycle_length

paste_position = first_key - cycle_length
while paste_position >= tmin + 30 - cycle_length:
    cmds.pasteKey(_ctrl_,t=(paste_position,paste_position),o='merge')
    paste_position -= cycle_length
#    cmds.pasteKey(_ctrl_,t=(paste_position,paste_position))