Merge pull request #5 from tacaswell/unpack_labeled_data_alternative

Vetter checks for python and IPython

lib/matplotlib/__init__.py

@@ -1588,13 +1588,12 @@ def foo(ax, *args, **kwargs)
 
     def param(func):
         new_sig = None
-        ver_info = sys.version_info
-        # py2.6 compatible version, use line below as soon as we can
-        python_has_signature = ver_info[0] > 2 and ver_info[1] > 2
-        # python_has_signature = ver_info.major > 2 and ver_info.minor > 2
-        python_has_wrapped = ver_info[0] > 2 and ver_info[1] > 1
-        # python_has_wrapped = ver_info.major > 2 and ver_info.minor > 1
-        if not python_has_signature:
+        python_has_signature = major >= 3 and minor1 >= 3
+        python_has_wrapped = major >= 3 and minor1 >= 2
+
+        # if in a legacy version of python and IPython is already imported
+        # try to use their back-ported signature
+        if not python_has_signature and 'IPython' in sys.modules:
             try:
                 import IPython.utils.signatures
                 signature = IPython.utils.signatures.signature