From train.py via fast.ai

fit_one_cycle.py

def fit_one_cycle(learn:Learner,
                  cyc_len:int,
                  max_lr:Union[Floats,slice]=default_lr, 
                  moms:Tuple[float,float]=(0.95,0.85), 
                  div_factor:float=25.,
                  pct_start:float=0.3, 
                  wd:float=None,
                  callbacks:Optional[CallbackList]=None, **kwargs) -> None:
    """Fit a model following the 1cycle policy."""
    max_lr = learn.lr_range(max_lr)
    callbacks = ifnone(callbacks, [])
    callbacks.append(OneCycleScheduler(learn, 
                                       max_lr, 
                                       moms=moms, 
                                       div_factor=div_factor,
                                       pct_start=pct_start, **kwargs))
    learn.fit(cyc_len, max_lr, wd=wd, callbacks=callbacks)