"size_average". When "reduce" is "False", returns a loss per
        batch element instead and ignores "size_average". Default:
        "None"
  * **reduction** (*str**, **optional*) -- Specifies the reduction
    to apply to the output: "'none'" | "'mean'" | "'sum'".
    "'none'": no reduction will be applied, "'mean'": the weighted
    mean of the output is taken, "'sum'": the output will be
    summed. Note: "size_average" and "reduce" are in the process
    of being deprecated, and in the meantime, specifying either of
    those two args will override "reduction". Default: "'mean'"

Shape:
      * Input: (N, C) or (C), where C = number of classes, or (N, C,
        d_1, d_2, ..., d_K) with K \geq 1 in the case of
        K-dimensional loss.
  * Target: (N) or (), where each value is 0 \leq
    \text{targets}[i] \leq C-1, or (N, d_1, d_2, ..., d_K) with K
    \geq 1 in the case of K-dimensional loss.
