Remove Zip[[a]These[X, a]]; it is unlawful.
Add &&& as a proper name for These#zip.
Deprecate These#zip; the name implies the existence of a lawful instance.
fix CoproductInstances. add Equal instanse
CoproductArbitrary
add CoproductTest
Merge pull request #499 from S11001001/topic/no-these-zip

Remove Zip on These and deprecate These#zip
Merge pull request #503 from xuwei-k/coproduct

fix CoproductInstances