anchor.diff:  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);
  
positive.code: 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;
  
negative.code: escape_char($s) -> $\s;                %\s = SPC
  escape_char($d) -> $\d;                %\d = DEL
  escape_char(C) -> C.
  
  %% 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.
  
  %% skip_until(String, Char1, Char2) -> String.
  %% skip_past(String, Char1, Char2) -> String.
  
  %% skip_until([C|_]=Cs, C1, C2) when C =:= C1 ; C =:= C2 -> Cs;
  %% skip_until([_|Cs], C1, C2) -> skip_until(Cs, C1, C2);
  %% skip_until([], _, _) -> [].
  
  skip_past([C|Cs], C1, C2) when C =:= C1 ; C =:= C2 -> Cs;
  skip_past([_|Cs], C1, C2) -> skip_past(Cs, C1, C2);
  skip_past([], _, _) -> [].
  