anchor.diff:    |  cell_array
     |  access
     |  t_AT t_FILLER? name
  +  |  t_END //really only applies in args, but let Natlab handle that
     ;
   
   access :
  
positive.code:   ;
  
  colon_expr :
       plus_expr (t_FILLER? t_COLON t_FILLER? plus_expr (t_FILLER? t_COLON t_FILLER? plus_expr)?)?
    ;
    
  plus_expr :
       binary_expr (t_FILLER? (t_PLUS | t_MINUS) t_FILLER? binary_expr)*
    ;
  
  binary_expr :
  
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 :
  