def __init__(self, firstName = '', lastName = ''):
    self._firstName = firstName
    self._lastName = lastName

@property
def firstName(self):
    return self._firstName

@property
def lastName(self):
    return self._lastName

@firstName.setter
def firstName(self, new_firstName):
    self._firstName = new_firstName

@lastName.setter
def lastName(self, new_lastName):
    self._lastName = new_lastName

self.users = []