global

def unfold8792(s)
  if s =~ UNFOLD_RE
    indicator = $1
    s = $'
    sub = case indicator
          when "\\"
            s.gsub!(/\\\n[ \t]*/, '')
          when "\\\\"
            s.gsub!(/\\\n[ \t]*\\/, '')
          else
            fail "indicator"    # Cannot happen
          end
    warn "** encountered RFC 8792 header without folded lines" unless sub
  end
  s
end