ast *createWhile (symbol *, symbol *, symbol *, ast *, ast *);
ast *createIf (ast *, ast *, ast *);
ast *createDo (symbol *, symbol *, symbol *, ast *, ast *);
ast *createWhile (symbol *, symbol *, symbol *, ast *, ast *);
ast *createIf (ast *, ast *, ast *);
ast *createDo (symbol *, symbol *, symbol *, ast *, ast *);