original_string: protected function belongsTo($class, $foreignKey): ?LightModel
      {
          $identifier = implode('_', [$class, $foreignKey]);
  
          if (! isset($this->_belongsTo[$identifier]))
          {
              if (! $this->getTable()->hasColumn($foreignKey))
              {
                  throw new ColumnMissingException($this->getTableName() . ' does not have column: ' . $foreignKey);
              }
  
              $this->_belongsTo[$identifier] = $class::getOneByKey($this->$foreignKey);
          }
  
          return $this->_belongsTo[$identifier];
      }
code: protected function belongsTo($class, $foreignKey): ?LightModel
      {
          $identifier = implode('_', [$class, $foreignKey]);
  
          if (! isset($this->_belongsTo[$identifier]))
          {
              if (! $this->getTable()->hasColumn($foreignKey))
              {
                  throw new ColumnMissingException($this->getTableName() . ' does not have column: ' . $foreignKey);
              }
  
              $this->_belongsTo[$identifier] = $class::getOneByKey($this->$foreignKey);
          }
  
          return $this->_belongsTo[$identifier];
      }
code_tokens: protected function belongsTo ( $ class , $ foreignKey ) : ? LightModel { $ identifier = implode ( '_' , [ $ class , $ foreignKey ] ) ; if ( ! isset ( $ this -> _belongsTo [ $ identifier ] ) ) { if ( ! $ this -> getTable ( ) -> hasColumn ( $ foreignKey ) ) { throw new ColumnMissingException ( $ this -> getTableName ( ) . ' does not have column: ' . $ foreignKey ) ; } $ this -> _belongsTo [ $ identifier ] = $ class :: getOneByKey ( $ this -> $ foreignKey ) ; } return $ this -> _belongsTo [ $ identifier ] ; }
docstring: Load the specified belongsTo relation model.
  
  @param $class
  @param $foreignKey
  @return LightModel
  @throws Exception
docstring_tokens: Load the specified belongsTo relation model .