Similar to :meth:`get_input_peer`, but for dialogs

def get_input_dialog(dialog):
    """Similar to :meth:`get_input_peer`, but for dialogs"""
    try:
        if dialog.SUBCLASS_OF_ID == 0xa21c9795:  # crc32(b'InputDialogPeer')
            return dialog
        if dialog.SUBCLASS_OF_ID == 0xc91c90b6:  # crc32(b'InputPeer')
            return types.InputDialogPeer(dialog)
    except AttributeError:
        _raise_cast_fail(dialog, 'InputDialogPeer')

    try:
        return types.InputDialogPeer(get_input_peer(dialog))
    except TypeError:
        pass

    _raise_cast_fail(dialog, 'InputDialogPeer')