=begin pod

=TITLE role Positional

    role Positional { ... }

Role for objects which support indexing them using C<postcircumfix:«[ ]»>
(usually list-like objects).  Example types with Positional role
include L<Parcel>, L<List>, L<Array>, L<Range>, and L<Buf>.

=head1 Methods

=head2 of

    method of()

Returns the type constraint for elements of the positional container. Defaults
to L<Mu>.

=end pod