Installation not possible on python3

[chbndrhnns]

Installation fails with

Collecting robotframework-unixfilesystemlibrary
  Downloading robotframework-unixfilesystemlibrary-0.1.0.tar.gz
    Complete output from command python setup.py egg_info:
    Traceback (most recent call last):
      File "<string>", line 1, in <module>
      File "/private/var/folders/n1/wsd2x88j48d6yr5dmwqs71m80000gn/T/pip-build-vedyzvvn/robotframework-unixfilesystemlibrary/setup.py", line 5, in <module>
        execfile(join(dirname(__file__), 'src', 'UnixFilesystemLibrary', 'version.py'))
    NameError: name 'execfile' is not defined

    ----------------------------------------
Command "python setup.py egg_info" failed with error code 1 in /private/var/folders/n1/wsd2x88j48d6yr5dmwqs71m80000gn/T/pip-build-vedyzvvn/robotframework-unixfilesystemlibrary/

Solution:
see other lib example