fix sample source syntax error

[youmjww]

Issue #, if available:
none

Description of changes:

A syntax error in the sample source was fixed.

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[codecov-io]

Codecov Report

Merging #260 into master will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master     #260   +/-   ##
=======================================
  Coverage   74.59%   74.59%           
=======================================
  Files          20       20           
  Lines         681      681           
=======================================
  Hits          508      508           
  Misses        128      128           
  Partials       45       45

Impacted Files	Coverage Δ
cfn/wrap.go	65.78% <100%> (ø)	⬆️

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