+ / 9. C<<1 setjmp()/longjmp() based exceptions, updated 2008-09-30
+ '----------------------------------------------------------------------- */
+#include <setjmp.h>
+#define try if(!(_exception_type=setjmp(_exception_env)))
+#define fail(E) longjmp(_exception_env, (E))
+#define else_switch_exceptions else switch(_exception_type)
+#define else_catch_exception(E) else if (_exception_type==(E))
+static jmp_buf _exception_env;
+static int _exception_type;
+/* .----------------------------------------------------------------------.
+ / 10. implementation of C<<1 library functions, updated 2008-01-26 xCh.