protected function isFunction($value): bool
    {
        return \is_callable($value) && ($value instanceof Closure || (\is_string($value) && \function_exists($value)));
    }
protected function isFunction($value): bool
    {
        return \is_callable($value) && ($value instanceof Closure || (\is_string($value) && \function_exists($value)));
    }
protected function isFunction ( $ value ) : bool { return \ is_callable ( $ value ) && ( $ value instanceof Closure || ( \ is_string ( $ value ) && \ function_exists ( $ value ) ) ) ; }
Check if something is a function.

@param mixed $value

@return bool
Check if something is a function .