--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/glimmerHMM/BCBio/GFF/_utils.py	Wed Jan 11 09:58:35 2012 -0500
@@ -0,0 +1,37 @@
+class defaultdict(dict):
+    """Back compatible defaultdict: http://code.activestate.com/recipes/523034/
+    """
+    def __init__(self, default_factory=None, *a, **kw):
+        if (default_factory is not None and
+            not hasattr(default_factory, '__call__')):
+            raise TypeError('first argument must be callable')
+        dict.__init__(self, *a, **kw)
+        self.default_factory = default_factory
+    def __getitem__(self, key):
+        try:
+            return dict.__getitem__(self, key)
+        except KeyError:
+            return self.__missing__(key)
+    def __missing__(self, key):
+        if self.default_factory is None:
+            raise KeyError(key)
+        self[key] = value = self.default_factory()
+        return value
+    def __reduce__(self):
+        if self.default_factory is None:
+            args = tuple()
+        else:
+            args = self.default_factory,
+        return type(self), args, None, None, self.items()
+    def copy(self):
+        return self.__copy__()
+    def __copy__(self):
+        return type(self)(self.default_factory, self)
+    def __deepcopy__(self, memo):
+        import copy
+        return type(self)(self.default_factory,
+                          copy.deepcopy(self.items()))
+    def __repr__(self):
+        return 'defaultdict(%s, %s)' % (self.default_factory,
+                                        dict.__repr__(self))
+