Revert "an example of domino"

This reverts commit caef4b0e80c4f70f4632a36f8ef0f861c70f364d.
Revert "Revert "an example of domino""

This reverts commit e7ca2fac0d83919d8dbdb419acd89cb1edd836b6.
Revert "Revert "Revert "an example of domino"""

This reverts commit 3d384555635530b0cd8405c01f5a2634a1624763.