{#
Generate an <author> or a <dc:creator> tag, based on the presence
of an email or not in the author's information.

Arguments:
 - author: the author to be used
#}
# if author:
## Try our best to retrieve an email address if wanted and possible
#   with author = format_author(author_email(author))
#     if '@' in author:
      <author>${author}</author>
#     else:
      <dc:creator>${author}</dc:creator>
#     endif
#   endwith
# endif