/// <summary>
/// Starts a block.
/// </summary>
/// <param name="blockType">Type of the block.</param>
/// <returns>The disposable used to end the block.</returns>
public IDisposable StartBlock(BlockType? blockType = null, string name = null)
{
EnsureNotTerminated();
_blockStack.Push(new BlockBuilder() { Type = blockType.GetValueOrDefault(BlockType.Text), Name = name });
return new DisposableAction(EndBlock);
}