# File lib/facet/lisp-format.rb, line 959
        def convert_char(ch)
          if [?\\, ?\n, ?\t, ?\r, ?\f, ?\v, ?\a, ?\e, ?\b, ?\s].include? ch
            ch.chr.inspect[1..-2]
          else
            if (ch & 0x7f) < 0x1f
              "\\C-" + convert_char(ch | 0x60)
            elsif ch >= 0x7f
              "\\M-" + convert_char(ch & 0x7f | 0x60)
            else
              ch
            end
          end
        end