Then statement to append to a logfile

[jaromil]

Then append the string 'log_line' to the logfile in '/var/log/w3c_did/created.log'
Then append the string 'log_line' to the logfile named by 'var_log'

Should append the 'log_line' string terminated by a newline to the indicated file.
It should error out in case log_line is not existing or not string output encoding.

[jaromil]

Then append the array of strings 'log_lines' to the logfile named by 'var_log'

To support for instance lists of lines to be appended in log that were created into a foreach in zenroom