anchor.diff:  assert_stmt: ASSERT test (COMMA test)?;
   
   compound_stmt: if_stmt | while_stmt | for_stmt | try_stmt | with_stmt | funcdef | classdef | decorated | async_stmt;
  -async_stmt: ASYNC (funcdef | with_stmt | for_stmt);
  +async_stmt: ASYNC (with_stmt | for_stmt);
   if_stmt: IF test COLON suite (elif_clause)* (else_clause)?;
   elif_clause: ELIF test COLON suite;
   while_stmt: WHILE test COLON suite (else_clause)?;
  
positive.code: parameters: OPEN_PAREN (typedargslist)? CLOSE_PAREN;
  typedargslist
      : (def_parameters COMMA)? args (COMMA def_parameters)? (COMMA kwargs)?
      |(def_parameters COMMA)? kwargs (COMMA def_parameters)? (COMMA args)?
      | def_parameters;
  args: STAR named_parameter;
  kwargs: POWER named_parameter;
  
negative.code: named_parameter: NAME (COLON test)?;
  varargslist
      : (vardef_parameters COMMA)? varargs (COMMA vardef_parameters)? (COMMA varkwargs)
      | vardef_parameters;
      
  varargs: STAR NAME;
  varkwargs: POWER NAME;
  