Format the defined attributes for a call to the Easypost service.
Takes an arrayref of attributes to serialize.
Defaults to the
Mark Allen <firstname.lastname@example.org>, Hunter McMillen <email@example.com>
This software is copyright (c) 2012 by Mark Allen.
This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.