From 0db1a711b38a718e04a5fb2b9cf0b6fbd7c925cf Mon Sep 17 00:00:00 2001
From: DoDaek <dbxor8960@naver.com>
Date: Sun, 15 Sep 2019 22:23:05 +0900
Subject: [PATCH 1/3] set: implement __and__ of set

---
 py/set.go       | 14 ++++++++++++++
 py/tests/set.py | 12 ++++++++++++
 2 files changed, 26 insertions(+)
 create mode 100644 py/tests/set.py

diff --git a/py/set.go b/py/set.go
index cc27a464..d899e105 100644
--- a/py/set.go
+++ b/py/set.go
@@ -111,6 +111,20 @@ func (s *Set) M__iter__() (Object, error) {
 	return NewIterator(items), nil
 }
 
+func (s *Set) M__and__(other Object) (Object, error) {
+	ret := NewSet()
+	b, ok := other.(*Set)
+	if !ok {
+		return nil, TypeError
+	}
+	for i := range b.items {
+		if _, ok := s.items[i]; ok {
+			ret.items[i] = SetValue{}
+		}
+	}
+	return ret, nil
+}
+
 // Check interface is satisfied
 var _ I__len__ = (*Set)(nil)
 var _ I__bool__ = (*Set)(nil)
diff --git a/py/tests/set.py b/py/tests/set.py
new file mode 100644
index 00000000..733a39e6
--- /dev/null
+++ b/py/tests/set.py
@@ -0,0 +1,12 @@
+# Copyright 2018 The go-python Authors.  All rights reserved.
+# Use of this source code is governed by a BSD-style
+# license that can be found in the LICENSE file.
+
+doc="__and__"
+a = {1, 2, 3}
+b = {2, 3, 4, 5}
+c = a.__and__(b)
+assert 2 in c
+assert 3 in c
+
+doc="finished"
\ No newline at end of file

From 542fc6844ec1885ca4280b879df9ac212615c8b4 Mon Sep 17 00:00:00 2001
From: DoDaek <dbxor8960@naver.com>
Date: Sun, 15 Sep 2019 22:37:02 +0900
Subject: [PATCH 2/3] set: add test code of set

---
 py/tests/set.py | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/py/tests/set.py b/py/tests/set.py
index 733a39e6..a641e976 100644
--- a/py/tests/set.py
+++ b/py/tests/set.py
@@ -9,4 +9,8 @@
 assert 2 in c
 assert 3 in c
 
+d = a & b
+assert 2 in d
+assert 3 in d
+
 doc="finished"
\ No newline at end of file

From ca6e4118a82bf5b9a2554473ee058e0db1fb70a8 Mon Sep 17 00:00:00 2001
From: DoDaek <dbxor8960@naver.com>
Date: Mon, 16 Sep 2019 08:39:35 +0900
Subject: [PATCH 3/3] set: modify year of the copyright and return value of the
 function

---
 py/set.go       | 2 +-
 py/tests/set.py | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/py/set.go b/py/set.go
index d899e105..f38b32ff 100644
--- a/py/set.go
+++ b/py/set.go
@@ -115,7 +115,7 @@ func (s *Set) M__and__(other Object) (Object, error) {
 	ret := NewSet()
 	b, ok := other.(*Set)
 	if !ok {
-		return nil, TypeError
+		return nil, ExceptionNewf(TypeError, "unsupported operand type(s) for &: '%s' and '%s'", s.Type().Name, other.Type().Name)
 	}
 	for i := range b.items {
 		if _, ok := s.items[i]; ok {
diff --git a/py/tests/set.py b/py/tests/set.py
index a641e976..e1500ed1 100644
--- a/py/tests/set.py
+++ b/py/tests/set.py
@@ -1,4 +1,4 @@
-# Copyright 2018 The go-python Authors.  All rights reserved.
+# Copyright 2019 The go-python Authors.  All rights reserved.
 # Use of this source code is governed by a BSD-style
 # license that can be found in the LICENSE file.