my declares the listed variables to be local (lexically) to the enclosing block, file, or
eval. If more than one value is listed, the list must be placed in parentheses.
The exact semantics and interface of TYPE and ATTRS are still evolving. TYPE is currently bound to the use of the
fields pragma, and attributes are handled using the
attributes pragma, or starting from Perl 5.8.0 also via the
Attribute::Handlers module. See "Private Variables via my()" in perlsub for details, and fields, attributes, and Attribute::Handlers.