public function getFunctionReflection(string $function): ReflectionFunction
    {
        $index = static::FUNCTION_CACHE . $function;

        return self::$reflections[$index]
            ?? self::$reflections[$index] = new ReflectionFunction($function);
    }
public function getFunctionReflection(string $function): ReflectionFunction
    {
        $index = static::FUNCTION_CACHE . $function;

        return self::$reflections[$index]
            ?? self::$reflections[$index] = new ReflectionFunction($function);
    }
public function getFunctionReflection ( string $ function ) : ReflectionFunction { $ index = static :: FUNCTION_CACHE . $ function ; return self :: $ reflections [ $ index ] ?? self :: $ reflections [ $ index ] = new ReflectionFunction ( $ function ) ; }
get a function's reflection.

@param string $function The function

@throws \ReflectionException

@return \ReflectionFunction
get a function s reflection .