LNode LockStmt(int startIndex)
{
var kw = MatchAny();
var p = Match((int) TT.LParen);
Match((int) TT.RParen);
var block = Stmt();
// line 2022
var expr = SingleExprInside(p, "lock (...)");
return F.Call(kw, expr, block, startIndex, block.Range.EndIndex);
}