Online PHP editor | output for RRKkp

<?php declare(strict_types=1); class CanBeStrung { public function __toString(): string { return 'I\'m highly strung'; } } function isItStringy($possibleStringType): bool { if (is_string($possibleStringType)) { return true; } if(is_callable([$possibleStringType, '__toString'])) { return true; } return false; } assert(isItStringy('a string') === true); assert(isItStringy(new CanBeStrung()) === true); assert(isItStringy(42) === false); assert(isItStringy(new stdClass()) === false);