message: Updated module overview
diff: """## Functions for working with arbitrarily nested sequences of elements.
  This module can perform operations on nested structures. A nested structure is a
  -Python sequence, tuple (including `namedtuple`), or dict that can contain
  -further sequences, tuples, and dicts.
  -
  -Structures are atom, or tuple or dict or list of constructed atoms and/or
  -other tuples/lists, or an atom object. Note, numpy arrays are considered
  -atoms.
  +Python collection that can contain further collections as well as other objects
  +called atoms. Note that numpy arrays are considered atoms.
  +
  +nest recognizes the following types of collections:
  + 1.tuple
  + 2.namedtuple
  + 3.dict
  + 4.orderedDict
  + 5.MutableMapping
  + 6.attr.s
  attr.s decorated classes (http://www.attrs.org) are also supported, in the
  same way as `namedtuple`.
  