anchor.diff:          ->
     %% passed checks so return Height
     Height;
  -check_height(Height) ->
  +check_height(_Height) ->
     %% failed checks so fail with atom indicating issue
     erlang:error(height_must_be_integer_1_to_9999).
   
  
positive.code:   %% valid so return atom
    julian;
  %% add other valid fractal algorithms here as they are created
  check_fractal_alg(FractalAlg) ->
    erlang:error(this_fractal_algorithm_not_implemented).
  
  %% get and validate image file name
  
negative.code: is_good_char(_C) ->
    %% this char ok
    ok.
  
  get_color_alg(BinaryMap) ->
    InitalColorAlg  = maps:get(<<"ColorAlg">>, BinaryMap),
    %% check validity and return if valid
    check_color_alg(InitalColorAlg).
  
  check_color_alg(InitialColorAlg) when InitialColorAlg =:= "simplest" ->
    simplest;
  check_color_alg(InitialColorAlg) when InitialColorAlg =:= <<"simplest">> ->
    simplest;
  check_color_alg(InitialColorAlg) when InitialColorAlg =:= <<"simplest2">> ->
    simplest2;
  check_color_alg(InitialColorAlg) when InitialColorAlg =:= "simplest2" ->
    simplest2;
  check_color_alg(InitialColorAlg) when InitialColorAlg =:= <<"simple16">> ->
    simple16;
  check_color_alg(InitialColorAlg) when InitialColorAlg =:= "simple16" ->
    simple16;
  check_color_alg(InitialColorAlg) when InitialColorAlg =:= <<"simple32">> ->
    simple32;
  check_color_alg(InitialColorAlg) when InitialColorAlg =:= "simple32" ->
    simple32;
  check_color_alg(InitialColorAlg) when InitialColorAlg =:= <<"blue32">> ->
    blue32;
  check_color_alg(InitialColorAlg) when InitialColorAlg =:= "blue32" ->
    blue32;
  check_color_alg(InitialColorAlg) when InitialColorAlg =:= <<"simple64">> ->
    simple64;
  check_color_alg(InitialColorAlg) when InitialColorAlg =:= "simple64" ->
    simple64;
  check_color_alg(_) ->
    erlang:error(unknown_color_alg).
  
  
  
  
  
  