cts, while
        ``byref`` only affects select objects.
    **kwds: extra keyword arguments passed to :py:class:`Pickler()`.

Raises:
   :py:exc:`PicklingError`: if pickling fails.

Examples:

    - Save current interpreter session state:

      >>> import dill
      >>> squared = lambda x: x*x
      >>> dill.dump_module() # save state of __main__ to /tmp/session.pkl

    - Save the state of an imported/importable module:

      >>> import dill
      >>> import pox
      >>> pox.plus_one = lambda x: x+1
      >>> dill.dump_module('pox_session.pkl', module=pox)

    - Save the state of a non-importable, module-type object:

      >>> import dill
      >>> from types import ModuleType
      >>> foo = ModuleType('foo')
      >>> foo.values = [1,2,3]
      >>> import math
      >>> foo.sin = math.sin
      >>> dill.dump_module('foo_session.pkl', module=foo, refimported=True)

    - Restore the state of the saved modules:

      >>> import dill
      >>> dill.load_module()
      >>> squared(2)
      4
      >>> pox = dill.load_module('pox_session.pkl')
      >>> pox.plus_one(1)
      2
      >>> foo = dill.load_module('foo_session.pkl')
      >>> [foo.sin(x) for x in foo.values]
      [0.8414709848078965, 0.9092974268256817, 0.1411200080598672]

    - Use `refimported` to save imported objects by reference:

      >>> import dill
      >>> from html.entities import html5
      >>> type(html5), len(html5)
      (dict, 2231)
      >>> import io
      >>> buf = io.BytesIO()
      >>> dill.dump_module(buf) # saves __main__, with html5 saved by value
      >>> len(buf.getvalue()) # pickle size in bytes
      71665
      >>> buf = io.BytesIO()
      >>> dill.dump_module(buf, refimported=True) # html5 saved by reference
      >>> len(buf.getvalue())
      438

*Changed in version 0.3.6:* Function ``dump_session()`` was renamed to
``dump_module()``.  Parameters ``main`` and ``byref`` were renamed to
``module`` and ``refimported``, respectively.

Note:
    Currently, ``dill.settings['byref']`` and ``dill.settings['recurse']``
    don't apply to this function.
)