Fix for py2only syntax

[benjaoming]

Fixes #21

[codecov-io]

Codecov Report

Merging #22 into master will increase coverage by 2.51%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master      #22      +/-   ##
==========================================
+ Coverage    86.2%   88.72%   +2.51%     
==========================================
  Files           4        4              
  Lines         203      204       +1     
==========================================
+ Hits          175      181       +6     
+ Misses         28       23       -5

Impacted Files	Coverage Δ
src/ifcfg/cli.py	85.71% <100%> (+85.71%)	⬆️

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