modbuiltins: Add NotImplemented builtin constant.
From https://docs.python.org/3/library/constants.html#NotImplemented :
"Special value which should be returned by the binary special methods
(e.g. __eq__(), __lt__(), __add__(), __rsub__(), etc.) to indicate
that the operation is not implemented with respect to the other type;
may be returned by the in-place binary special methods (e.g. __imul__(),
__iand__(), etc.) for the same purpose. Its truth value is true."
Some people however appear to abuse it to mean "no value" when None is
a legitimate value (don't do that).
diff --git a/py/mpconfig.h b/py/mpconfig.h
index a5aacc8..560fdce 100644
--- a/py/mpconfig.h
+++ b/py/mpconfig.h
@@ -479,6 +479,11 @@
#define MICROPY_PY_BUILTINS_REVERSED (1)
#endif
+// Whether to define "NotImplemented" special constant
+#ifndef MICROPY_PY_BUILTINS_NOTIMPLEMENTED
+#define MICROPY_PY_BUILTINS_NOTIMPLEMENTED (0)
+#endif
+
// Whether to set __file__ for imported modules
#ifndef MICROPY_PY___FILE__
#define MICROPY_PY___FILE__ (1)