code: public SDVariable hardTanh(String name, SDVariable in) {
          validateFloatingPoint("hard Tanh", in);
          SDVariable result = f().hardTanh(in);
          return updateVariableNameAndReference(result, name);
      }
docs: Element-wise hard tanh function:<br>
  out[i] = -1 if in[i] <= -1<br>
  out[1] = in[i] if -1 < in[i] < 1<br>
  out[i] = 1 if in[i] >= 1<br>
  
  @param name Output variable name
  @param in   Input variable
  @return Output variable