private void FetchDocumentIndicator(bool isStartToken)
{
// Reset the indentation level.
UnrollIndent(-1);
// Reset simple keys.
RemoveSimpleKey();
simpleKeyAllowed = false;
// Consume the token.
var start = cursor.Mark();
Skip();
Skip();
Skip();
Token token = isStartToken ? (Token)new DocumentStart(start, cursor.Mark()) : new DocumentEnd(start, start);
tokens.Enqueue(token);
}