Your parameterized role consists of two new things: parameter declarations
and a 'role' block.

Parameters are declared using the the /parameter manpage keyword which very
much resembles the Moose/has manpage. You can use any option that the
Moose/has manpage accepts. The default value for the 'is' option is 'ro' as
that's a very common case. Use 'is => 'bare'' if you want no accessor.
These parameters will get their values when the consuming class (or role)
uses the Moose/with manpage. A parameter object will be constructed with
these values, and passed to the 'role' block.

The 'role' block then uses the usual the Moose::Role manpage keywords to
build up a role. You can shift off the parameter object to inspect what the
consuming class provided as parameters. You use the parameters to customize
your role however you wish.