Uncommenting change_parameter_to_variable example

variations.pl

@@ -249,12 +249,12 @@ biocham: bifurcations(E1,1e-6,1e-4,time:1000000).
 
 
     
-%:- doc('\\begin{example}
-% ').
-% :- biocham_silent(clear_model).
-% :- biocham(load('library:examples/cell_cycle/Qu_et_al_2003.bc')).
-% :- change_parameter_to_variable(k1).
-% :- list_model.
-% :- biocham("dose_response(k1,1,1000,time:200,show:'CycB-CDK~{p1}'")).
-% :- doc('\\end{example}
-% ').
+:- doc('\\begin{example}
+\\clearmodel
+\\trace{
+biocham: load(library:examples/cell_cycle/Qu_et_al_2003.bc).
+biocham: change_parameter_to_variable(k1).
+biocham: list_model.
+biocham: dose_response(k1,1,1000,time:200,show:CycB-CDK~{p1}).
+}
+\\end{example}').