let return_html_msg = mk_return_fun pp_msg "text/html"
let return_html_raw = mk_return_fun null_pp "text/html"
let return_xml_raw = mk_return_fun null_pp "text/xml"
let return_html_msg = mk_return_fun pp_msg "text/html"
let return_html_raw = mk_return_fun null_pp "text/html"
let return_xml_raw = mk_return_fun null_pp "text/xml"