anchor.diff:    |  cell_array
     |  access
     |  t_AT t_FILLER? name
  -  |  t_END //really only applies in args, but let Natlab handle that
  +  //|  t_END //really only applies in args, but let Natlab handle that
     ;
   
   access :
  
positive.code: 
  //start symbol
  program :
       //empty
    |  script
    |  function_list
    |  class_def
    ;
  
  stmt :
       stmt_body t_FILLER? stmt_separator
    ;
  
  stmt_separator :
       t_LINE_TERMINATOR
    |  t_SEMICOLON
    |  t_COMMA
    |  EOF
    ;
  
  stmt_body :
       
    |  expr
    |  expr t_FILLER? t_ASSIGN t_FILLER? expr
    |  (t_GLOBAL | t_PERSISTENT) (t_FILLER? name)+
    |  t_SHELL_COMMAND
    |  t_TRY sep_stmt_list (t_CATCH sep_stmt_list)? t_FILLER? t_END
    |  t_SWITCH t_FILLER? expr t_FILLER? stmt_separator (t_FILLER? t_CASE t_FILLER? expr sep_stmt_list)* (t_FILLER? t_OTHERWISE sep_stmt_list)? t_FILLER? t_END
    |  t_IF t_FILLER? expr sep_stmt_list (t_FILLER? t_ELSEIF t_FILLER? expr sep_stmt_list)* (t_FILLER? t_ELSE sep_stmt_list)? t_FILLER? t_END
    |  t_BREAK
    |  t_CONTINUE
    |  t_RETURN
    |  t_WHILE t_FILLER? expr sep_stmt_list t_FILLER? t_END
    |  t_FOR t_FILLER? (name t_FILLER? ASSIGN t_FILLER? expr | LPAREN t_FILLER? name t_FILLER? ASSIGN t_FILLER? expr t_FILLER? RPAREN) sep_stmt_list t_FILLER? t_END
    ;
  
  sep_stmt_list :
       t_FILLER? stmt_separator (t_FILLER? stmt)*
    ;
  
  //precedence from: http://www.mathworks.com/access/helpdesk/help/techdoc/matlab_prog/f0-40063.html
  
negative.code: expr :
       short_or_expr
    |  t_AT t_FILLER? input_params t_FILLER? expr
    //|  t_COLON //really only applies in args, but let Natlab handle that
    ;
  
  short_or_expr :
  