Code python contient des erreurs , méthode non correct

Bonjour,
J'ai développé ce code python, mais le résultat n'est celui que j’attends :

from abc import ABC, abstractmethod
 
 
class InvoiceCalc:
    """
    Calcul des montants à facturer
    """
    __taux_tva = 0.21
    __instance = None
 
    @classmethod
    def singleton(taux_tva):
        if not InvoiceCalc.__instance:
            InvoiceCalc.__instance = InvoiceCalc()
            InvoiceCalc.__instance.__taux_tva = InvoiceCalc(taux_tva)
 
    def __init__(self):
     pass
 
    def compute_perform(self, price, dur):
        """ calcule le montant à facturer (htva, tva, ttc)
            pour cet employé "emp" et
            pour cette durée de prestation  "dur"
            avec le tarif horaire "price" = emp.price
        """
        montant = dur * price
        return self.compute_expense(montant)
 
    def compute_expense(self, exp):
        """ calcule et retourne le montant à facturer (htva, tva, ttc)
            pour cette dépense "exp"
        """
        montant = exp
        tva = montant * self.__taux_tva
        montant_ttc = montant + tva
        return ( montant, tva, montant_ttc )
 
class Project:
    """
    Gestion des enregistrements du temps d'un employé
    sur un projet pour un client.
    A ne pas modifier !
    """
    def __init__(self, project="", client=""):
        self.__client = ""
        self.__project = project
        self.__perform_l = []
        self.__expense_l = []
        self.__client = client
 
    def perform(self, emp, det, dur):
        if isinstance(emp, Employee):
            self.__perform_l.append({
                "name":     emp.name,
                "detail":   det,
                "duration": float(dur),
                "price":    emp.price
            })
 
    def expense(self, emp, subject, amount):
        self.__expense_l.append({
            "name":   emp.name,
            "detail": subject,
            "amount": float(amount)
        })
 
    def __iter__(self):
        self.index = 0
        self.inv_calc = InvoiceCalc()
        return self
 
    def __next__(self):
        if self.index >= len(self.__expense_l):
            raise StopIteration
        data = self.__expense_l[self.index]
        self.index += 1
        amount = data['amount']
        htva, tva, ttc = self.inv_calc.compute_expense(amount)
        return f'{data["detail"]},{htva},{tva},{ttc}'
        #return data
 
    def __str__(self):
        # templates
        header_s = \
    """
    Client  : {1}
    Projet  : {2}
 
    """
        header_perform_s = \
    """
    Détail des prestations (h, €)
    """
        header_expense_s = \
    """
    Détail des dépenses (€)
    """
        perform_str = "{2:8} {0:26} {5:>6.2f}€/h {1:>6.2f}h {4:>6.0f}€\n"
        expense_str = "{2:8} {0:26}                   {4:>6.0f}€\n"
        title_str = "{2:^8} {0:^26} {5:^8} {1:^9} {4:^7}\n"
        t_p = 0  # total prestation
        t_i = 0  # total facturation
        t_e = 0  # total expense
        final_fs = ""
 
        # header
        final_fs += header_s.format("", self.__client, self.__project)
 
        # body "perform"
        final_fs += header_perform_s
        final_fs += title_str.format("TASK", "DUR", "PERSON", "DEPT", "INV", "PRICE")
        for data in self.__perform_l:
            inv_c = InvoiceCalc()
            to_invoice_tuple = inv_c.compute_perform(data["price"], data["duration"])
            final_fs += perform_str.format(
                data["detail"],
                data["duration"],
                data["name"],
                "",
                to_invoice_tuple[0],
                data["price"]
            )
            t_p += data["duration"]
            t_i += to_invoice_tuple[0]
        final_fs += "\n" + perform_str.format("Total perform", t_p, "", "", t_i, 0) + "\n"
 
        # body "expense"
        final_fs += header_expense_s
        final_fs += title_str.format("EXPENSE", "", "PERSON", "DEPT", "INV", "")
        for data in self.__expense_l:
            inv_c = InvoiceCalc()
            to_invoice_tuple = inv_c.compute_expense(data["amount"])
            final_fs += expense_str.format(
                data["detail"],
                0,
                data["name"],
                "",
                to_invoice_tuple[0]
            )
            t_e += to_invoice_tuple[0]
        final_fs += "\n" + expense_str.format("Total expense", 0, "", "", t_e) + "\n"
 
        # footer
        final_fs += "\n" + expense_str.format("Total général", 0, "******", "***********", t_e + t_i) + "\n"
 
        return final_fs
 
 
class Employee(ABC):
    def __init__(self, name):
        self.name = name
 
    @property
    @abstractmethod
    def price(self):
        return self.price
        #pass
 
    @property
    @abstractmethod
    def department(self):
        return self.department
        #pass
 
    @classmethod
    def factory(self, name, function):
        if function == "Geek":
            return Geek(name)
        elif function == "hardware":
            return HardwareGeek(name)
        elif function == "technical manager":
            return TechnicalManager(name)
        elif function == "account manager":
            return AccountManager(name)
        else:
            raise ValueError("Unknown employee type")
        #return EmployeeFake(name)
 
 
class EmployeeFake(Employee):
    department = "circus"
    price = 15
 
 
class EmployeeHardware(Employee):
    department = "hardware"
    project_o = Project("installation de deux PC", "Lehman Brothers Bank")
    emp = "kim"
    det = {"achat matériel MAC", "configuration matériel", "installation chez client"}#"detail"
    dur = 0
    project_o.perform(emp, det, dur)
    detail = det
 
class Geek(EmployeeHardware):
    price = 60
 
 
class HardwareGeek(EmployeeHardware):
    price = 0
 
    def pricing_intel(self):
        self.price = 65
        return self.price
        # pass
 
    def pricing_mac(self):
 
        detail = {"achat matériel MAC", "configuration matériel", "installation chez client"}
        if detail == "achat matériel MAC":
            self.price = 75
        if detail == "configuration matériel":
            self.price = 50
        elif detail == "installation chez client":
            self.price = 50
        else :self.price = 75
 
       
class TechnicalManager(EmployeeHardware):
    price = 90
 
 
class AccountManager(Employee):
    department = "account"
    price = 100
 
 
 
if __name__ == '__main__':
    #
 
    # 1)
    kim = Employee.factory("Kim", "hardware" )  # return HardwareGeek object
    ali = Employee.factory("Ali", "hardware" )  # return HardwareGeek object
    albert = Employee.factory("Albert", "technical manager") # return TechnicalManager object
    sophie = Employee.factory("Sophie", "account manager")   # return AccountManager object
 
    # 2)
    project_o = Project("installation de deux PC", "Lehman Brothers Bank")
 
    # 3)
    project_o.perform(albert, "réunion avec client", 1)
    kim.pricing_intel() # on passe au tarif "PC"
    project_o.perform(kim, "achat matériel PC", 0.5)
    kim.pricing_mac()   # on passe au tarif "MAC"
    project_o.perform(kim, "achat matériel MAC", 1.5)
    project_o.perform(ali, "configuration matériel", 2)
    project_o.perform(ali, "installation chez client", 3)
    project_o.perform(albert, "remise des clés", 0.5)
    project_o.perform(sophie, "convention avec le client", 0.5)
 
    # on ajoute des dépenses
    project_o.expense(kim, "deux PC et accessoires", 1500)
    project_o.expense(kim, "trois MAC et accessoires", 4500)
 
     
    # 4)
    print("CSV")
 
    project_it = iter(project_o)
    while True:
        try:
            # iteration
            csv = next(project_it)
            print(csv)
        except StopIteration:
            # quand tous les enregistrements ont été reçus
            break

Le problème est dans la méthode pricing_mac() (l208) de la classe HardwareGeek : quand je l'appelle cette méthode, je veux que le tarif change, mais ce n'est pas le cas.

Pouvez-vous m'aider s'il vous plaît ?