src/Primitive/String/String.php
public function has($needle, $caseSensitive = true)
    {
        return StaticStringy::contains(
            $this->string, $this->retrieveValue($needle), $this->getBoolable($caseSensitive)
        );
    }
public function has($needle, $caseSensitive = true)
    {
        return StaticStringy::contains(
            $this->string, $this->retrieveValue($needle), $this->getBoolable($caseSensitive)
        );
    }
Return true if the string contains $needle, false otherwise. By default,
the comparison is case-sensitive, but can be made insensitive by setting
$caseSensitive to false.

@param mixed $needle
@param mixed $caseSensitive
@return bool