py: fix bound __index__

Author: aisk

py/method.go

@@ -192,6 +192,11 @@ func newBoundMethod(name string, fn interface{}) (Object, error) {
 		m.method = func(_ Object) (Object, error) {
 			return f()
 		}
+	// M__index__() (Int, error)
+	case func() (Int, error):
+		m.method = func(_ Object) (Object, error) {
+			return f()
+		}
 	// M__add__(other Object) (Object, error)
 	case func(Object) (Object, error):
 		m.method = func(_ Object, other Object) (Object, error) {

py/tests/int.py

@@ -24,6 +24,10 @@
 assert repr(1000000000000000000000000000000) == "1000000000000000000000000000000"
 assert repr(-1000000000000000000000000000000) == "-1000000000000000000000000000000"
 
+doc="index"
+assert True.__index__() == 1
+assert False.__index__() == 0
+
 doc="test overflow"
 assert int("1000000000000000000") == 10**18
 assert int("-1000000000000000000") == -(10**18)