loss element in the batch. Note that for some losses, there
        multiple elements per sample. If the field "size_average" is
        set to "False", the losses are instead summed for each
        minibatch. Ignored when reduce is "False". Default: "True"
  * **ignore_index** (*int**, **optional*) -- Specifies a target
    value that is ignored and does not contribute to the input
    gradient. When "size_average" is "True", the loss is averaged
    over non-ignored targets. Default: -100

  * **reduce** (*bool**, **optional*) -- Deprecated (see
    "reduction"). By default, the losses are averaged or summed
    over observations for each minibatch depending on
    "size_average". When "reduce" is "False", returns a loss per
    batch element instead and ignores "size_average". Default:
    "True"

  * **reduction** (*str**, **optional*) -- Specifies the reduction
    to apply to the output: "'none'" | "'mean'" | "'sum'".
