code: public SDVariable sigmoidDerivative(String name, SDVariable x, SDVariable wrt) {
          validateFloatingPoint("sigmoidDerivative", x);
          SDVariable result = f().sigmoidDerivative(x, wrt);
          return updateVariableNameAndReference(result, name);
      }
docs: Element-wise sigmoid function derivative: dL/dIn given input and dL/dOut
  
  @param name Output variable name
  @param x    Input Variable
  @param wrt  Gradient at the output - dL/dOut. Must have same shape as the input
  @return Output variable