The function get_trial_list()
tries to execute the expression handed
over and returns a list of the outcome.
try_get_model(expr)
A list of length three with the following elements is returned
The object returned by the expression, if applicable, or otherwise NULL
A warning message, if applicable, or otherwise NULL
An error message, if applicable, or otherwise NULL
An expression to be executed.
The function tries to execute the expression handed over. It case of an error it does not stop execution but in any case returns a list as specified in chapter Value. If execution of the expression was successful, the results are stored in element Model. In case of warnings or errors, the messages are silently redirected to the elements Warning or Error, respectively.