Implemented Callback sample #209

Job	Run time
Check Ruby Samples ubuntu-latest	1m 25s
Exercise Python examples on ubuntu-latest	1m 58s
Code formatting	12s
Check Ruby Samples macos-latest	1m 45s
Exercise Python examples on macos-latest	3m 46s
Build Windows fetch	3m 12s
Build Windows vcpkg	8m 28s
Build ubuntu-20.04 gcc os	52s
Build ubuntu-20.04 gcc fetch	1m 16s
Build ubuntu-20.04 gcc vcpkg	4m 19s
Build ubuntu-20.04 clang os	1m 13s
Build ubuntu-20.04 clang fetch	1m 57s
Build ubuntu-20.04 clang vcpkg	4m 21s
Build macos-latest gcc os	2m 43s
Build macos-latest gcc fetch	2m 38s
Build macos-latest gcc vcpkg	2m 35s
Build macos-latest clang os	2m 20s
Build macos-latest clang fetch	2m 10s
Build macos-latest clang vcpkg	2m 17s
	49m 27s

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