anchor.diff:    ;
   
   term
  -  : factor ( options{greedy=true;}: multiplying_operator factor )*
  +  : factor ( : multiplying_operator factor )*
     ;
   
   terminal_aspect
  
positive.code: 
  relation
    : shift_expression
      ( options{greedy=true;}: relational_operator shift_expression )?
    ;
  
  relational_operator
  
negative.code: // `a op -b' - use `a op (-b)' instead).
  // (3.2.2004, e.f.)
  simple_expression
    : ( PLUS | MINUS )? term ( : adding_operator term )*
    ;
  
  simple_simultaneous_statement
  