anchor.diff:     | '<<'
      | '>>'
      | '<'
  -   | '">'
  +   | '>'
      | '<='
      | '>='
      | '=='
  -   | '!'
  -   | '='
  +   | '!='
      | '&'
      | '^'
      | '|'
  
positive.code:    ;
  
  function_name_part
     : IDENTIFIER
     | function_name_part '.' IDENTIFIER
     ;
  
  statements
  
negative.code:    ;
  
  lvalue_expression_list
     : lvalue_expression (',' lvalue_expression)*
     ;
  
  init_list
     : element (',' element)*
     ;
  
  term
  