cont.py

class Eroare(Exception):
    "Clasa de baza pentru exceptii de utilizator"
    pass

class FonduriInsuficiente(Eroare):
    "Exceptie generata cand soldul unui cont este mai mic decat suma solicitata"
    pass

class Cont:
    def __init__(self, numar, sold):
        self.numar = numar
        self.sold = sold
    def __str__(self):
        return "Contul {} are un  sold de {} RON.".\
            format(self.numar, round(self.sold, 2))
    def depune(self, suma):
        self.sold += suma
    def retrage(self, suma):
        try:
            if self.sold >= suma:
                self.sold -= suma
            else:
                necesar = suma - self.sold
                raise FonduriInsuficiente("Fonduri insuficiente! Necesar {} RON.".\
                    format(round(necesar, 2)))
        except FonduriInsuficiente as e:
                print(e)

if __name__ == "__main__":
    c = Cont("SV523BTV74635643", 500.34)
    # Contul SV523BTV74635643 are un sold de 500.34 RON.
    print(c)              
    c.depune(20.12)
    # Fonduri insuficiente! Necesar 502.63 RON.
    c.retrage(1023.09)