def do_debug(self, args):
        """Implementation of 'coverage debug'."""

        if not args:
            self.help_fn("What information would you like: data, sys?")
            return ERR
        for info in args:
            if info == 'sys':
                print("-- sys ----------------------------------------")
                for line in info_formatter(self.coverage.sysinfo()):
                    print(" %s" % line)
            elif info == 'data':
                print("-- data ---------------------------------------")
                self.coverage.load()
                print("path: %s" % self.coverage.data.filename)
                print("has_arcs: %r" % self.coverage.data.has_arcs())
                summary = self.coverage.data.summary(fullpath=True)
                if summary:
                    filenames = sorted(summary.keys())
                    print("\n%d files:" % len(filenames))
                    for f in filenames:
                        print("%s: %d lines" % (f, summary[f]))
                else:
                    print("No data collected")
            else:
                self.help_fn("Don't know what you mean by %r" % info)
                return ERR
        return OK
Implementation of 'coverage debug'.