/// <summary>
 ///     Fills the list provided with the element matching the filter provided
 /// </summary>
 /// <param name="retVal">The list to be filled with the element matching the condition expressed in the filter</param>
 /// <param name="filter">The filter to apply</param>
 public override void Fill(List <INamable> retVal, BaseFilter filter)
 {
     Expression.Fill(retVal, filter);
     InitialValue.Fill(retVal, filter);
     Condition.Fill(retVal, filter);
 }