Detect default support using __missing__

https://docs.python.org/3.6/reference/datamodel.html#object.__missing__

Author: dhimmel

pandas/core/series.py

@@ -2133,13 +2133,12 @@ def map_f(values, f):
             else:
                 map_f = lib.map_infer
 
-        default_dict_types = collections.Counter, collections.defaultdict
-        if isinstance(arg, default_dict_types):
-            dict_with_default = arg
-            arg = lambda x: dict_with_default[x]
-
-        elif isinstance(arg, dict):
-            arg = self._constructor(arg, index=arg.keys())
+        if isinstance(arg, dict):
+            if hasattr(arg, '__missing__'):
+                dict_with_default = arg
+                arg = lambda x: dict_with_default[x]
+            else:
+                arg = self._constructor(arg, index=arg.keys())
 
         if isinstance(arg, Series):
             indexer = arg.index.get_indexer(values)