SF patch 672098: Three __contains__ implementations

Contributed by Jp Calderone.

Lib/lib-tk/Canvas.py

@@ -39,6 +39,8 @@ class CanvasItem:
         return self._keys
     def has_key(self, key):
         return key in self.keys()
+    def __contains__(self, key):
+        return key in self.keys()
     def addtag(self, tag, option='withtag'):
         self.canvas.addtag(tag, option, self.id)
     def bbox(self):

Lib/plat-riscos/riscosenviron.py

@@ -32,6 +32,8 @@ class _Environ:
     def has_key(self, key):
         value = riscos.getenv(key)
         return value<>None
+    def __contains__(self, key):
+        return riscos.getenv(key) is not None
     def update(self, dict):
         for k, v in dict.items():
             riscos.putenv(k, v)

Lib/xml/sax/xmlreader.py

@@ -321,6 +321,9 @@ class AttributesImpl:
     def has_key(self, name):
         return self._attrs.has_key(name)
 
+    def __contains__(self, name):
+        return self._attrs.has_key(name)
+
     def get(self, name, alternative=None):
         return self._attrs.get(name, alternative)