SWI-Prolog offers the possibility to log the interaction with the
user on a file.64A similar
facility was added to Edinburgh C-Prolog by Wouter Jansweijer.
All Prolog interaction, including warnings and tracer output, are
written on the protocol file.
Start protocolling on file File. If there is already a
protocol file open then close it first. If File exists it is
Equivalent to protocol/1,
but does not truncate the File if it exists.
Stop making a protocol of the user interaction. Pending output is
flushed on the file.
True if a protocol was started with protocol/1
and unifies File with the current protocol output file.