original_string: public function getTtl(): ?int
      {
          $maxAge = $this->getMaxAge();
  
          return null !== $maxAge ? $maxAge - $this->getAge() : null;
      }
code: public function getTtl(): ?int
      {
          $maxAge = $this->getMaxAge();
  
          return null !== $maxAge ? $maxAge - $this->getAge() : null;
      }
code_tokens: public function getTtl ( ) : ? int { $ maxAge = $ this -> getMaxAge ( ) ; return null !== $ maxAge ? $ maxAge - $ this -> getAge ( ) : null ; }
docstring: Returns the response's time-to-live in seconds.
  
  It returns null when no freshness information is present in the response.
  
  When the responses TTL is <= 0, the response may not be served from cache without first
  revalidating with the origin.
  
  @final
docstring_tokens: Returns the response s time - to - live in seconds .