anchor.diff:  bs_getlast_false_index(<<B/bits>>) -> bs_getlast_true_index(bits_oper:bs_not(<<B/bits>>)).
   bs_getfirst_false_index(<<B/bits>>) -> bs_getfirst_true_index(bits_oper:bs_not(<<B/bits>>)).
   
  +%TODO Test It : number of true bits, number of false bits
  +bs_count_true(<<I:1/bits,B/bits>>) when I == <<0:1>> -> 0 + bs_count_true(<<B/bits>>);
  +bs_count_true(<<I:1/bits,B/bits>>) when I == <<1:1>> -> 1 + bs_count_true(<<B/bits>>);
  +bs_count_true(<<>>) -> 0.
  +
  +bs_count_false(<<I:1/bits,B/bits>>) when I == <<0:1>> -> 1 + bs_count_false(<<B/bits>>);
  +bs_count_false(<<I:1/bits,B/bits>>) when I == <<1:1>> -> 0 + bs_count_false(<<B/bits>>);
  +bs_count_false(<<>>) -> 0.
   
   %TODO :improve performance and code design... same with bitwise comprehension if possible ? or more arithmetic ?
   % unary bitwise not
  
positive.code: 	%%Last false bit
  	io:fwrite("| ~8s          ||  ~8s  ||  ~8s  |~n",["LFB","???",bs_to_string( bs_getlast_false(Bin))]),
  	io:fwrite("| ~8s          ||  ~8s  ||  ~8.10B  |~n",["LFB indx","???",bs_getlast_false_index(Bin)]),
  
  	ok.
  
  
negative.code: -export([bs_and/2,bs_or/2,bs_xor/2,bs_sl/2,bs_sr/2]).
  -export([bs_getfirst_true/1,bs_getfirst_false/1,bs_getlast_true/1,bs_getlast_false/1]).
  -export([bs_getfirst_true_index/1,bs_getfirst_false_index/1,bs_getlast_true_index/1,bs_getlast_false_index/1]).
  -export([bs_count_true/1,bs_count_false/1]).
  -export([bs_show/1,bs_autotest/1,bs_oper_boolalg_test/2,bs_oper_boolsimplif_test/3]).
  
  %%existing bitstring operators : 
  