anchor.diff:  	   {unop, fun erlang:term_to_binary/1,  smaller_tree(term)},
   	   {unop, fun erlang:list_to_binary/1,  smaller_tree(list)},
   	   {unop, fun erlang:atom_to_binary/1,  smaller_tree(atom)},
  -	   {unop, fun lists:iolist_to_binary/1, smaller_tree(iolist)},
  +%NotImplemented:	   {unop, fun lists:iolist_to_binary/1, smaller_tree(iolist)},
   	   {unop, fun erlang:'md5'/1,           smaller_tree(iolist)}
   		 ])]);
   %% Type unions:
  
positive.code:     oneof([{literal, tuple(any())},
  	   {unop, fun erlang:list_to_tuple/1, smaller_tree(list)},
  	   {binop, fun erlang:'make_tuple'/2,
  	    smaller_tree(integer), smaller_tree(term)},
  	   {binop, fun erlang:'append_element'/2,
  	    smaller_tree(tuple), smaller_tree(term)}
  	   ]);
  program_tree(list) ->
      oneof([{literal, list(any())},
  
negative.code: 	   {unop, fun erlang:'byte_size'/1,  smaller_tree(binary)},
  	   {unop, fun erlang:'bit_size'/1,   smaller_tree(binary)},
  	   {unop, fun erlang:'iolist_size'/1,smaller_tree(oneof([list,binary]))},
  %NotImplemented:	   {unop, fun erlang:'crc32'/1,      smaller_tree(binary)},
  %NotImplemented:	   {unop, fun erlang:'adler32'/1,    smaller_tree(binary)},
  
  	   {binop, oneof([fun erlang:'+'/2,
  			  fun erlang:'-'/2,
  