code: public SDVariable firstIndex(String name, SDVariable in, Condition condition, int... dimensions) {
          return firstIndex(name, in, condition, false, dimensions);
      }
docs: First index reduction operation.<br>
  Returns a variable that contains the index of the first element that matches the specified condition (for each
  slice along the specified dimensions)
  
  @param name       Name of the output variable
  @param in         Input variable
  @param condition  Condition to check on input variable
  @param dimensions Dimensions to reduce over. If dimensions are not specified, full array reduction is performed
  @return Reduced array of rank (input rank - num dimensions)