Write String {msg} in the channel log file, if it was opened with ch_logfile(). The text "ch_log():" is prepended to the message to make clear it came from this function call and make it easier to find in the log file. When {handle} is passed the channel number is used for the message. {handle} can be a Channel or a Job that has a Channel. The Channel must be open for the channel number to be used.

Can also be used as a method:

'did something'->ch_log()