class_docstr: A generic container for immutable data that can be accessed either by
  numeric index or by key. This is similar to an
  :class:`collections.OrderedDict` except that the keys are optional and
  iteration over it returns the values instead of keys.
  
  This is the base class for both :class:`.Column` and :class:`.Row`.
  
  :param values:
      A sequence of values.
  :param keys:
      A sequence of keys.
code: def __repr__(self):
      return self.__str__()
  
imports: from collections import OrderedDict
  from collections.abc import Sequence
  from agate.utils import memoize
label_desc: Use image node_id 6 for calling the MappedSequence obj's underlying member method code with example usage: obj.__repr__() and returns: self