public ParseTree getChild(int i) {return children!=null && i>=0 && i<children.size() ? children.get(i) : null;}

public ParseTree getChild ( int i ) { return children != null && i >= 0 && i < children . size ( ) ? children . get ( i ) : null ; }
public override IParseTree GetChild(int i){return children != null && i >= 0 && i < children.Count ? children[i] : null;}
