ENH: Include sharedoc function

tests/utils/test_sharedoc.py

@@ -0,0 +1,21 @@
+from zipline.testing import ZiplineTestCase
+from zipline.utils.sharedoc import copydoc
+
+
+class TestSharedoc(ZiplineTestCase):
+
+    def test_copydoc(self):
+        def original_docstring_function():
+            """
+            My docstring brings the boys to the yard.
+            """
+            pass
+
+        @copydoc(original_docstring_function)
+        def copied_docstring_function():
+            pass
+
+        self.assertEqual(
+            original_docstring_function.__doc__,
+            copied_docstring_function.__doc__
+        )