code: private function defineRelation(Model $model, $columnName) {
          $otherModelName = ucfirst(camel_case(substr($columnName, 0, strpos($columnName, self::ID_SUFFIX)))); // TODO: prettify
  
          if (!in_array($otherModelName, array_keys($this->models))) {
              //$this->app['log']->warning(sprintf('Found foreign id %s in model %s, but no model with name %s was registered', $columnName, $model->getName(), $otherModelName));
              return;
          }
  
          //$this->app['log']->info(sprintf('%s has a %s', $model->getName(), $otherModelName));
  
          $this->relations[$model->getName()][] = new Relation($model, $this->models[$otherModelName], Relation::BELONGS_TO);
      }
docs: Defines the relation between given model and the model corresponding to the column name.
  Does nothing if the other model was not declared in init().
  
  @param $model      Model the model which has given columnName.
  @param $columnName String the column name, which corresponds to another model.