modify the description
rename: zeroed -> zeroed/example_test
add a comment
rename: interface.assign -> assignment/example_test
modify the comment
Add the MIT license
rename: share.interface -> share/interface
rename: share.implement -> share/implement
S <-> P
rename: type.assertion -> types/assertion_example_test
rename: type.switch -> types/switch_example_test
add doc.go
remove main|recursive
add import for share
add example for package var