checker is a ContentChecker

def check_hash(self, checker, filename, tfp):
        """
        checker is a ContentChecker
        """
        checker.report(
            self.debug,
            "Validating %%s checksum for %s" % filename)
        if not checker.is_valid():
            tfp.close()
            os.unlink(filename)
            raise DistutilsError(
                "%s validation failed for %s; "
                "possible download problem?"
                % (checker.hash.name, os.path.basename(filename))
            )