libhash-case-perl 1.020-1 (i386 binary) in ubuntu xenial

 Hash::Case is the base class for various classes which tie special
 treatment for the casing of keys. Be aware of the differences in
 implementation: Lower and Upper are tied native hashes: these
 hashes have no need for hidden fields or other assisting data
 structured. A case Preserve hash will actually create three hashes.