def _dump(self, service, grep=None):
if grep:<EOL><INDENT>return self.adb_shell('<STR_LIT>'.format(service, grep))<EOL><DEDENT>return self.adb_shell('<STR_LIT>'.format(service))<EOL>
Perform a service dump.

        :param service: Service to dump.
        :param grep: Grep for this string.
        :returns: Dump, optionally grepped.