message level ~section fmt ... send a message of the specified level and section.

Do not use this function directly, instead include the instantiation of a Self functor, and use corresponding logging functions, e.g.,

  include Self()
  (* ... *)
  info "created some %s" "thing"

progress ?note ?stage ?total name sends a progress report. This function should be used by the main components only, while plugins should use the report_progress function from the Self() interface. All parameters defaults to None.