n &#39;exp_range&#39; scaling function:
            gamma**(cycle iterations)
        scale_fn: Custom scaling policy defined by a single
            argument lambda function, where
            0 &lt;= scale_fn(x) &lt;= 1 for all x &gt;= 0.
            mode paramater is ignored
        scale_mode: {&#39;cycle&#39;, &#39;iterations&#39;}.
            Defines whether scale_fn is evaluated on
            cycle number or cycle iterations (training
            iterations since start of cycle). Default is &#39;cy