public virtual void RemoveTrainAt(int index)
{
Contract.Requires <ArgumentOutOfRangeException>(index >= 0 && index < Trains.Count());
Contract.Assume(index < Trains.Count());
this._trains.RemoveAt(index);
}
/// <summary>
/// Moves a train at the specified index one step up.
/// </summary>
/// <param name="index">The index of the train.</param>
public virtual void MoveTrainUpAt(int index)
{
Contract.Requires <ArgumentOutOfRangeException>(index >= 0 && index < Trains.Count());
Contract.Assume(index < this._trains.Count);
Train train = this._trains[index];
this._trains.RemoveAt(index);
this._trains.Insert(index - 1, train);
}