'DEPRECATED since IPython 5.0
Enable event loop integration with PyQt4.
Parameters
app : Qt Application, optional.
Running application to use.  If not given, we probe Qt for an
existing application object, and create a new one if none is found.
Notes
This methods sets the PyOS_InputHook for PyQt4, which allows
the PyQt4 to integrate with terminal based applications like
IPython.
If ``app`` is not given we probe for an existing one, and return it if
found.  If no existing app is found, we create an :class:`QApplication`
as follows::
from PyQt4 import QtCore
app = QtGui.QApplication(sys.argv)'

def enable(self, app=None):

    warn('This    function    is    deprecated    since    IPython    5.0    and    will    be    removed    in    future    versions.', DeprecationWarning, stacklevel=2)
    from IPython.lib.inputhookqt4 import create_inputhook_qt4
    (app, inputhook_qt4) = create_inputhook_qt4(self.manager, app)
    self.manager.set_inputhook(inputhook_qt4)
    if _use_appnope():
        from appnope import nope
        nope()
    return app
