code: public SDVariable sum(String name, SDVariable x, int... dimensions) {
          return sum(name, x, false, dimensions);
      }
docs: Sum array reduction operation, optionally along specified dimensions
  
  @param x          Input variable
  @param dimensions Dimensions to reduce over. If dimensions are not specified, full array reduction is performed
  @return Output variable: reduced array of rank (input rank - num dimensions) if keepDims = false, or
  of rank (input rank) if keepdims = true