src/Http/Header.php
public function hasCacheControlDirective($key)
    {
        return isset($this->computedCacheControl[$key]) || \array_key_exists($key, $this->computedCacheControl);
    }
public function hasCacheControlDirective($key)
    {
        return isset($this->computedCacheControl[$key]) || \array_key_exists($key, $this->computedCacheControl);
    }
public function hasCacheControlDirective ( $ key ) { return isset ( $ this -> computedCacheControl [ $ key ] ) || \ array_key_exists ( $ key , $ this -> computedCacheControl ) ; }
Returns true if the Cache-Control directive is defined.

@param string $key The Cache-Control directive

@return bool true if the directive exists, false otherwise
Returns true if the Cache - Control directive is defined .