anchor.diff:  WITH    :   'with';
   WHILE   :   'while';
   
  +M       :   'm/';
  +S       :   's/';
  +
   // §3.10.1 Integer Literals
   
   IntegerLiteral
  
positive.code: statement
      :   namespace
      |   enumeration
      |   if_block
      |   foreach_block
      |   while_block
      |   dowhile_block
      |   RETURN expression?
      |   PRINT expression?
      |   DEBUG expression?
  
negative.code:         expression
      ;
  
  m
      :   M expression SLASH expression SLASH params
      ;
  
  s   :   S expression SLASH expression SLASH expression SLASH params
      ;
  
  assign
      :   Identifier '=' expression
      ;
  
  tuple
      :   '(' expressions? ')'
      ;
  
  list
      :   '[' expressions? ']'
      ;
  
  seq
      :   '<' expressions? '>'
      ;
  
  dict
      :   '{' expressions? '}'
      ;
  
  primary
  