code: def do_du(self, params):
          
          self.show_output(pretty_bytes(self._zk.du(params.path)))
docs: \x1b[1mNAME\x1b[0m
          du - Total number of bytes under a path
  
  \x1b[1mSYNOPSIS\x1b[0m
          du [path]
  
  \x1b[1mOPTIONS\x1b[0m
          * path: the path (default: cwd)
  
  \x1b[1mEXAMPLES\x1b[0m
          > du /
          90