rate via initial_lr = max_lr/div_factor Default: 25
  * **final_div_factor** (*float*) -- Determines the minimum
    learning rate via min_lr = initial_lr/final_div_factor
    Default: 1e4

  * **three_phase** (*bool*) -- If "True", use a third phase of
    the schedule to annihilate the learning rate according to
    'final_div_factor' instead of modifying the second phase (the
    first two phases will be symmetrical about the step indicated
    by 'pct_start').

  * **last_epoch** (*int*) -- The index of the last batch. This
    parameter is used when resuming a training job. Since *step()*
    should be invoked after each batch instead of after each
    epoch, this number represents the total number of *batches*
    computed, not the total number of epochs computed. When
    last_epoch=-1, the schedule is started from the beginning.
    Default: -1

  * **verbose** (*bool*) -- If "True", prints a message to stdout
