How to use the pudb.shell.SetPropagatingDict function in pudb

def pudb_shell(_globals, _locals):
    """
    This example shell runs a classic Python shell. It is based on
    run_classic_shell in pudb.shell.

    """
    # Many shells only let you pass in a single locals dictionary, rather than
    # separate globals and locals dictionaries. In this case, you can use
    # pudb.shell.SetPropagatingDict to automatically merge the two into a
    # single dictionary. It does this in such a way that assignments propogate
    # to _locals, so that when the debugger is at the module level, variables
    # can be reassigned in the shell.
    from pudb.shell import SetPropagatingDict
    ns = SetPropagatingDict([_locals, _globals], _locals)

    try:
        import readline
        import rlcompleter
        HAVE_READLINE = True
    except ImportError:
        HAVE_READLINE = False

    if HAVE_READLINE:
        readline.set_completer(
                rlcompleter.Completer(ns).complete)
        readline.parse_and_bind("tab: complete")
        readline.clear_history()

    from code import InteractiveConsole
    cons = InteractiveConsole(ns)

def cmdline_get_namespace():
            curframe = self.debugger.curframe

            from pudb.shell import SetPropagatingDict
            return SetPropagatingDict(
                    [curframe.f_locals, curframe.f_globals],
                    curframe.f_locals)

def run_classic_shell(locals, globals, first_time):
    if first_time:
        banner = "Hit Ctrl-D to return to PuDB."
    else:
        banner = ""

    ns = SetPropagatingDict([locals, globals], locals)

    if HAVE_READLINE:
        readline.set_completer(
                rlcompleter.Completer(ns).complete)

    from code import InteractiveConsole
    cons = InteractiveConsole(ns)

    cons.interact(banner)

def pudb_shell(_globals, _locals):
    try:
        tty_name = os.path.basename(os.ttyname(sys.stdout.fileno()))
    except OSError:
        tty_name = 'unknown'

    # This makes it so that assignments in the shell act like globals
    # assignments
    ns = SetPropagatingDict([_locals, _globals], _locals)

    return run_shell(ns, ns, quiet=True,
        history_file='~/.mypython/history/pudb_%s_history' % tty_name,
        in_out=emoji_pudb)

def run_bpython_shell(locals, globals, first_time):
    ns = SetPropagatingDict([locals, globals], locals)

    import bpython.cli
    bpython.cli.main(locals_=ns)