anchor.diff:      |   expression op=('*'|'/'|'%') expression                           # Mul
       |   expression op=('+'|'-') expression                               # Add
       |   expression op=('<<' | '>>>' | '>>') expression                   # Shifts
  -    |   expression op=('<=' | '>=' | '>' | '<') expression               # Rel  
  -    |   expression op=('==' | '!=') expression                           # Equ 
  +    |   expression op=('<=' | '>=' | '>' | '<') expression               # Rel
  +    |   expression op=('==' | '!=') expression                           # Equ
       |   expression '&' expression                                        # BAnd
       |   expression '^' expression                                        # BXor
       |   expression '|' expression                                        # BOr
  
positive.code:     :   block
      ;
  
  literal                                                
      :   IntegerLiteral                                                # IntLit
      |   FloatingPointLiteral                                          # FloatLit
      |   CharacterLiteral                                              # CharLit
  
negative.code:     ;
  
  formalParameterList
      :   formalParameter (',' formalParameter)*
      ;
  
  formalParameter
  