add a simple class which can wrap any block.
Revert "add a simple class which can wrap any block."

This reverts commit bbda197fbec0e282656d013a9d45832c20afc80b.
Revert "Revert "add a simple class which can wrap any block.""

This reverts commit a19270ea548aaf0c0fb1d3a3be5328cfc3551020.
Revert "Revert "Revert "add a simple class which can wrap any block."""

This reverts commit ace315ebb0e891a6cdd7fb9e178291df0a356517.
Revert "Revert "add a simple class which can wrap any block.""

This reverts commit a19270ea548aaf0c0fb1d3a3be5328cfc3551020.