cannot pass named tuples into `fieldtypes()`?

Lines 3 to 4 in a639217

    
           function add_tuple_sum(x::NT, y::NT) where { NT<:NamedTuple } 
        
               @assert all(fieldtypes(x) .== fieldtypes(y))

I get a method error (no method matching fieldtypes(::NamedTuple))...

Also I get no methods for fieldvalues (UndefVarError; maybe this is in some package I don't know?):

Lines 7 to 8 in a639217

    
           values_of_x = fieldvalues(x) 
        
           values_of_y = fieldvalues(y)

namedtuple should be NamedTuple?

Line 11 in a639217

nt = namedtuple(names_of_values, values )

	function add_tuple_sum(x::NT, y::NT) where { NT<:NamedTuple }
	@assert all(fieldtypes(x) .== fieldtypes(y))