[addresses issue #7] implemented `has(key)' method

pickledb.py

@@ -74,7 +74,11 @@ def rem(self, key):
         del self.db[key]
         self._dumpdb(self.fsave)
         return True
-
+
+    def has(self, key):
+        '''Returns True if key exists; False otherwise'''
+        return self.db.has_key(key)
+
     def lcreate(self, name):
         '''Create a list'''
         self.db[name] = []

tests.py

@@ -42,6 +42,12 @@ def testRemoveString(self):
         c = self.db.get('var')
         self.assertTrue(a == b and b != c and c == None)
 
+    def testHas(self):
+        a = self.teststring
+        self.db.set('var', a)
+        self.assertTrue(self.db.has('var'))
+        self.db.rem('var')
+        self.assertFalse(self.db.has('var'))
 
 if __name__ == '__main__':
-    unittest.main()
+    unittest.main()