PHP 7 Compatibility

I am getting the following errors when running a PHP 7 compatibility check:

FILE: /wp-content/plugins/constant-contact-api/classes/class.kwscampaign.php
————————————————————————————————————————
FOUND 1 ERROR AFFECTING 1 LINE
————————————————————————————————————————
48 | ERROR | ‘clone’ is a reserved keyword introduced in PHP version 5.0 and cannot be invoked as a function (T_CLONE)
————————————————————————————————————————

FILE: /wp-content/plugins/constant-contact-api/classes/class.kwscontact.php
————————————————————————————————————————-
FOUND 1 ERROR AFFECTING 1 LINE
————————————————————————————————————————-
127 | ERROR | ‘clone’ is a reserved keyword introduced in PHP version 5.0 and cannot be invoked as a function (T_CLONE)
————————————————————————————————————————-

FILE: /wp-content/plugins/constant-contact-api/classes/class.kwscontactlist.php
————————————————————————————————————————-
FOUND 1 ERROR AFFECTING 1 LINE
————————————————————————————————————————-
45 | ERROR | ‘clone’ is a reserved keyword introduced in PHP version 5.0 and cannot be invoked as a function (T_CLONE)
————————————————————————————————————————-

FILE: /wp-content/plugins/constant-contact-api/vendor/guzzlehttp/promises/src/functions.php
—————————————————————————————————————————————————
FOUND 0 ERRORS AND 1 WARNING AFFECTING 1 LINE
—————————————————————————————————————————————————
485 | WARNING | Function name “__next_coroutine” is discouraged; PHP has reserved all method names with a double underscore prefix for future use
—————————————————————————————————————————————————