code: def _dump(self, service, grep=None):
          
          if grep:
              return self.adb_shell('dumpsys {0} | grep "{1}"'.format(service, grep))
          return self.adb_shell('dumpsys {0}'.format(service))
docs: Perform a service dump.
  
          :param service: Service to dump.
          :param grep: Grep for this string.
          :returns: Dump, optionally grepped.