code: public function setSex( $sex )
      {
          if (!in_array( $sex, self::$sexTypes )) {
              throw new InvalidArgumentException( sprintf( 'Invalid sex (%s)', $sex ) );
          }
  
          $this->sex = $sex;
  
          return $this;
      }
docs: @param  string $sex
  
  @return $this
  @throws \InvalidArgumentException