class HealthcareProfessional:
    def __init__(self, name):
        self.name = name

    def perform_duty(self):
        raise NotImplementedError("Subclass must implement abstract method")

class Doctor(HealthcareProfessional):
    def perform_duty(self):
        return f"Dr. {self.name} is diagnosing patients."

class Nurse(HealthcareProfessional):
    def perform_duty(self):
        return f"Nurse {self.name} is administering medication."

professionals = [
    Doctor("Andrew"),
    Nurse("John")
]