Logs.SrcSourceSources.
create ?doc name is a new log source. name is the name of the source; it doesn't need to be unique but it is good practice to prefix the name with the name of your package or library (e.g. "mypkg.network"). doc is a documentation string describing the source, defaults to "undocumented". The initial reporting level of the source is defined by Logs.level.
set_level src l sets the report level of src to l. Only applications should use this function directly, see usage conventions.
pp ppf src prints an unspecified representation of src on ppf.