code: public SDVariable rsub(String name, SDVariable x) {
          val result = sameDiff.f().rsub(this,x);
          return sameDiff.updateVariableNameAndReference(result,name);
      }
docs: Reverse subtraction operation: elementwise {@code x - this}<br>
  If this and x variables have equal shape, the output shape is the same as the inputs.<br>
  Supports broadcasting: if this and x have different shapes and are broadcastable, the output shape is broadcast.
  
  @param name Name of the output variable
  @param x    Variable to perform operation with
  @return Output (result) SDVariable