class_docstr: An abstract dataset class that supports slicing.
  
  This is a dataset class that supports slicing.
  A dataset class inheriting this class should implement
  three methods: :meth:`__len__`, :meth:`keys`, and
  :meth:`get_example_by_keys`.
  
  Users can easily create sliceable datasets using
  :class:`~chainercv.chainer_experimental.datasets.sliceable.GetterDataset`
  or
  :class:`~chainercv.chainer_experimental.datasets.sliceable.TupleDataset`.
class_docstr_tok: ["An","abstract","dataset","class","that","supports","slicing",".","This","is","a","dataset","class","that","supports","slicing",".","A","dataset","class","inheriting","this","class","should","implement","three","methods",":",":","meth",":","`","__len__","`",",",":","meth",":","`","keys","`",",","and",":","meth",":","`","get_example_by_keys","`",".","Users","can","easily","create","sliceable","datasets","using",":","class",":","`","~chainercv.chainer_experimental.datasets.sliceable.GetterDataset","`","or",":","class",":","`","~chainercv.chainer_experimental.datasets.sliceable.TupleDataset","`","."]
docstr: Return data of an example by keys
  
  Args:
      index (int): An index of an example.
      key_indices (tuple of ints): A tuple of indices of requested keys.
  
  Returns:
      tuple of data
docstr_tok: ["Return","data","of","an","example","by","keys","Args",":","index","(","int",")",":","An","index","of","an","example",".","key_indices","(","tuple","of","ints",")",":","A","tuple","of","indices","of","requested","keys",".","Returns",":","tuple","of","data"]
code: def get_example_by_keys(self, index, key_indices):
      """Return data of an example by keys
  
      Args:
          index (int): An index of an example.
          key_indices (tuple of ints): A tuple of indices of requested keys.
  
      Returns:
          tuple of data
      """
      raise NotImplementedError
  
imports: import numbers
  import numpy
  import six
  import chainer
label_desc: Use image node_id 3 for calling the SliceableDataset obj's underlying member method code with example usage: obj.get_example_by_keys(index, key_indices) without return types