<?php
/**
 * @author  Andrey Helldar <helldar@ai-rus.com>
 *
 * @since   2017-02-20
 * @since   2017-03-08 Add statuses for user.
 */
return array(
    1 => 'Unknown method',
    2 => 'Unknown error!',

    10 => 'Access denied.',
    11 => 'Unauthorized.',

    20 => 'Successfully.',
    21 => 'Success!',
    22 => 'Error.',

    30 => 'Login successfully.',
    31 => 'Logout successfully.',

    40 => 'User successfully authorized!',
    41 => 'User authenticated successfully!',
    42 => 'User already authorized!',
    43 => 'User successfully updated!',

    50 => 'Activated successfully!',
    51 => 'Activation failed!',
    52 => 'Deactivated successfully!',
    53 => 'Deactivation failed!',
);

<?php
/**
 * @author  Andrey Helldar <helldar@ai-rus.com>
 *
 * @since   2017-02-20
 * @since   2017-03-08 Add statuses for user.
 * @since   2017-03-20 Replace codes to HTTP Codes.
 */
return array(
    1 => 'Unknown method!',
    2 => 'Unknown error!',
    3 => 'Access denied.',

    200 => 'OK',
    201 => 'Created',
    202 => 'Accepted',
    204 => 'No content',
    
    301 => 'Moved',
    302 => 'Found',
    304 => 'Not Modified',
    
    400 => 'Bad Request',
    401 => 'Unauthorized',
    403 => 'Forbidden',
    404 => 'Not Found',
    409 => 'Conflict',
    
    500 => 'Internal Server Error',
    502 => 'Bad Gateway',
    503 => 'Service Unvailable',
);

Replace codes to HTTP Codes.
Replace codes to HTTP Codes.