load a MOC from a dict object and display it in Aladin Lite widget
            Arguments:
            moc_dict: the dict containing the MOC cells. Key are the HEALPix orders,
                      values are the pixel indexes, eg: {"1":[1,2,4], "2":[12,13,14,21,23,25]} 
            moc_options: dictionary object

def add_moc_from_dict(self, moc_dict, moc_options = {}):
        """ load a MOC from a dict object and display it in Aladin Lite widget
            Arguments:
            moc_dict: the dict containing the MOC cells. Key are the HEALPix orders,
                      values are the pixel indexes, eg: {"1":[1,2,4], "2":[12,13,14,21,23,25]} 
            moc_options: dictionary object"""
        self.moc_dict = moc_dict
        self.moc_options = moc_options
        self.moc_from_dict_flag = not self.moc_from_dict_flag