anchor.diff:    |  cell_array
     |  access
     |  AT name
  -  |  name AT name input_params?
     ;
   
   access :
  
positive.code:   ;
  
  element_list :
       (element) (element_separator+ element)*
    ;
    
  element :
  
negative.code: 
  cell_access :
       (var_access) (LCURLY arg_list RCURLY)*
    |  name AT name
    ;
    
  var_access :
       (name) (DOT name)*
    ;
  
  arg_list :	
  