set_modes
Description:
Sets the easing modes for each key frame inside this.
If this does not hold any key frame, modes.length key frames will be created; if
this already has key frames, modes must have at least as many elements as the number of key
frames.
Parameters:
| this | |
| modes |
an array of easing modes, one for each key frame |
| n_modes |
the number of easing modes |