Fix doctest error

fn/underscore.py

@@ -80,6 +80,8 @@ def call(self, name, *args, **kwargs):
         )
 
     def __getattr__(self, name):
+        if name == '__wrapped__':  # Guard for recursive call by doctest
+            raise AttributeError
         attr_name = _random_name()
         return self.__class__(
             F(operator.attrgetter(name)) << F(self),

test.py

@@ -1,6 +1,11 @@
+import doctest
 import unittest
 
 from tests import *
 
 if __name__ == "__main__":
+
+    import tests.test_doctest
+    doctest.testmod(tests.test_doctest)
+
     unittest.main()

tests/__init__.py

@@ -1,6 +1,7 @@
 from .test_banker_queue import *
 from .test_composition import *
 from .test_curry import *
+from .test_doctest import *
 from .test_finger_tree import *
 from .test_iterators import *
 from .test_linked import *

tests/test_doctest.py

@@ -0,0 +1 @@
+from fn import _