public function set_credentials($user, $pass)
    {
        $this->username = $user;
        $this->password = $pass;
        return $this;
    }
public function set_credentials($user, $pass)
    {
        $this->username = $user;
        $this->password = $pass;
        return $this;
    }
public function set_credentials ( $ user , $ pass ) { $ this -> username = $ user ; $ this -> password = $ pass ; return $ this ; }
Set the credentials to use for authentication.

@param string $user (Required) The username to authenticate with.
@param string $pass (Required) The password to authenticate with.
@return $this A reference to the current instance.
Set the credentials to use for authentication .