anchor.diff:  
   statement
       :   namespace
  -    |   enumeration
       |   if_stmt
       |   foreach_stmt
       |   while_stmt
  
positive.code:         expression
      ;
  
  m
      :   M expression SLASH expression SLASH params
      ;
  
  s   :   S expression SLASH expression SLASH expression SLASH params
      ;
  
  assign
  
negative.code:     :   DO block WHILE expression
      ;
  
  primary
      :   '(' expression ')'
      |   literal
      |   identifiers
      ;
  
  identifiers
      :   COMMA* Identifier (COMMA+ Identifier*)*
      ;
  
  literal
      :   IntegerLiteral
      |   RangeLiteral
      |   FloatingPointLiteral
      |   CharacterLiteral
      |   StringLiteral
      |   BooleanLiteral
      |   NullLiteral
      ;
  
  expressions
      :   expressions_flow
      |   expressions_inline
      ;
  
  expressions_flow
      :   INDENT expressions_inline (NL expressions_inline)* NL* DEDENT
      ;
  
  expressions_inline
      :   expression (COMMA expression)*
      ;
  
  