docs: def remote_space_available(self, search_pattern=r"(\d+) bytes free"):
          """Return space available on remote device."""
          remote_cmd = 'system "df {}"'.format(self.folder_name)
          remote_output = self.ssh_ctl_chan.send_command_expect(remote_cmd)
          for line in remote_output.splitlines():
              if self.folder_name in line:
                  space_available = line.split()[-3]
                  break
          return int(space_available)