anchor.diff:      | (test | star_expr) (comp_for | (COMMA (test | star_expr))* COMMA?)
       ;
   
  +star_expr
  +    : STAR expr
  +    ;
  +
   classdef
       : CLASS name (OPEN_PAREN arglist? CLOSE_PAREN)? COLON suite
  +    ;
  +
  +funcdef
  +    : ASYNC? DEF name OPEN_PAREN typedargslist? CLOSE_PAREN (ARROW test)? COLON suite
       ;
   
   arglist
  
positive.code: 
  test_nocond
      : logical_test
      | lambdef_nocond
      ;
  
  lambdef_nocond
      : LAMBDA varargslist? COLON test_nocond
      ;
  
  logical_test
  
negative.code:     : test (AS expr)?
      ;
  
  // Python 2 : EXCEPT test COMMA name
  // Python 3 : EXCEPT test AS name
  except_clause
      : EXCEPT (test (COMMA name | AS name)?)? COLON suite
      ;
  