Execution example::

  tokenize TokenMecab "東京都"
  # [
  #   [
  #     0,
  #     1545812631.661493,
  #     0.0002415180206298828
  #   ],
  #   [
  #     {
  #       "value": "東京",
  #       "position": 0,
  #       "force_prefix": false,
  #       "force_prefix_search": false
  #     },
  #     {
  #       "value": "都",
  #       "position": 1,
  #       "force_prefix": false,
  #       "force_prefix_search": false
  #     }
  #   ]
  # ]
