 = ... 
%   problem.opts.chosen_option = ... 
%
% or
%
%   new_opts = structure_something 
%   problem.opts = new_opts;
%
% Typically, all these changes inside the object are "monitored" by the
% object and it might not allow you to change the value (e.g. invalid
% option settings, wrong dimension of |xinit|, ...). In such a case you will
% get an error message and the structure is not changed. Or you might get a
% warning that something has been changed but it looks suspicious so it
% just poi