-void ast_set_output(FILE *out);
-void print_expression(const expression_t *expression);
-void print_initializer(const initializer_t *initializer);
-void print_ast(const translation_unit_t *unit);
-void print_indent(void);
-void print_declaration(const entity_t *entity);
-void print_entity(const entity_t *entity);
-void change_indent(int delta);
-void *allocate_ast(size_t size);