lib/Model/Shopper.php
public function setGender($gender)
    {
        $allowed_values = array('Male', 'Female', 'Other');
        if (!is_null($gender) && (!in_array($gender, $allowed_values))) {
            throw new \InvalidArgumentException("Invalid value for 'gender', must be one of 'Male', 'Female', 'Other'");
        }
        $this->container['gender'] = $gender;

        return $this;
    }
public function setGender($gender)
    {
        $allowed_values = array('Male', 'Female', 'Other');
        if (!is_null($gender) && (!in_array($gender, $allowed_values))) {
            throw new \InvalidArgumentException("Invalid value for 'gender', must be one of 'Male', 'Female', 'Other'");
        }
        $this->container['gender'] = $gender;

        return $this;
    }
Sets gender
@param string $gender The shopper's gender
@return $this