code: public function getFamiliarity($user = null)
      {
          if (is_null($user)) {
              $user = $this->getUser(false);
          }
          if (is_object($user)) {
              $user = $user->primaryKey;
          }
          $familarityKey = md5($user);
          if (!isset($this->_familiarity[$familarityKey])) {
              $this->_familiarity[$familarityKey] = false;
              $familiarityClass = Yii::$app->classes['ObjectFamiliarity'];
              if (!empty($user)) {
                  $attributes = [];
                  $attributes[$this->objectField] = $this->owner->primaryKey;
                  $attributes[$this->userField] = $user;
                  $this->_familiarity[$familarityKey] = $familiarityClass::find()->where($attributes)->one();
                  if (empty($this->_familiarity[$familarityKey])) {
                      $this->_familiarity[$familarityKey] = new $familiarityClass();
                      $this->_familiarity[$familarityKey]->attributes = $attributes;
                  }
              }
          }
  
          return $this->_familiarity[$familarityKey];
      }
docs: Get familiarity.
  
  @param [[@doctodo param_type:user]] $user [[@doctodo param_description:user]] [optional]
  
  @return [[@doctodo return_type:getFamiliarity]] [[@doctodo return_description:getFamiliarity]]