code: def pipe(self, cmd1, cmd2, quiet=False, estimated_size=None, **kwa):
          
          if self.has_pv and not quiet:
              pv = "pv" if estimated_size is None else "pv --size {}".format(estimated_size)
              return self.shell("{} | {}| {}".format(cmd1, pv, cmd2), **kwa)
          else:
              return self.shell("{} | {}".format(cmd1, cmd2), **kwa)
docs: Executes commands