anchor.diff:  chars([C|Cs]) -> [C|chars(Cs)];
   chars([]) -> [].
   
  -%% Block Comment:
  -%%  Provide a sensible error when people attempt to include nested
  -%%  comments because currently the parser cannot process them without
  -%%  a rebuild. But simply exploding on a '#|' is not going to be that
  -%%  helpful.
  -
  -block_comment(TokenChars) ->
  -    %% Check we're not opening another comment block.
  -    case string:str(TokenChars, "#|") of
  -        0 -> skip_token; %% No nesting found
  -        _ -> {error, "illegal nested block comment"}
  -    end.
  -
   hex_char(C) when C >= $0, C =< $9 -> true;
   hex_char(C) when C >= $a, C =< $f -> true;
   hex_char(C) when C >= $A, C =< $F -> true;
  
positive.code: escape_char($s) -> $\s;                %\s = SPC
  escape_char($d) -> $\d;                %\d = DEL
  escape_char(C) -> C.
  
negative.code: base1([C|Cs], Base, SoFar) when C >= $a, C =< $z, C < Base + $a - 10 ->
      Next = SoFar * Base + (C - $a + 10),
      base1(Cs, Base, Next);
  base1([C|Cs], Base, SoFar) when C >= $A, C =< $Z, C < Base + $A - 10 ->
      Next = SoFar * Base + (C - $A + 10),
      base1(Cs, Base, Next);
  