def logger(self, msg, level, warn=False):
        """
        Print log message *msg* to stdout.

        Parameters
        -----------

         msg : str
            String to print on the screen

         level : int
            Log-level. Only the messages with a level higher than the
            current verbose level will be shown.

         warn : bool
            Warning flag. If True, the message will be displayed
            regardless of its log-level.

        """
        if level<self.verbose or (warn and level<=self.verbose):
            dt = time.time() - self.t_start
            outstr = '\n' if level<2 else ''
            outstr += format(dt, '4.2f')+'\t'
            outstr += level*'-'
            outstr += msg
            print(outstr, file=sys.stdout)
Print log message *msg* to stdout.

        Parameters
        -----------

         msg : str
            String to print on the screen

         level : int
            Log-level. Only the messages with a level higher than the
            current verbose level will be shown.

         warn : bool
            Warning flag. If True, the message will be displayed
            regardless of its log-level.