Error in Slicer 4.6.2

[tokjun]

When the PercutaneousApproachAnalaysis module was installed from Slicer Extensions, 3D Slicer 4.6.2 failed to load the module with the following error:

[GCC 4.2.1 Compatible Clang 3.1 ((tags/RELEASE_31/final))] on darwin
>>> Traceback (most recent call last):
  File "/Applications/Slicer.app/Contents/Extensions-25516/PercutaneousApproachAnalysis/lib/Slicer-4.6/qt-scripted-modules/PercutaneousApproachAnalysis.py", line 14, in __init__
    parent.helpText = string.Template("""
NameError: global name 'string' is not defined