getattr()

class Celsius:
    def __init__(self, temperature = 0):
        self.temperature = temperature

    def to_fahrenheit(self):
        return (self.temperature * 1.8) + 32

    def get_temperature(self):
        print("Getting value")
        return self._temperature

    def set_temperature(self, value):
        if value < -273:
            raise ValueError("Temperature below -273 is not possible")
        print("Setting value")
        self._temperature = value

    temperature = property(get_temperature,set_temperature)

# --------------------------------------

def working(aclass, method_name, set_value):
    amount = aclass()
    amount.temperature = set_value

    # get access to method using its name as string
    method = getattr(amount, method_name)

    # execute method
    print(method())

# send method name as string
working(Celsius, 'to_fahrenheit', 373)

# --------------------------------------

def working2(obj, method, set_value):
    obj.temperature = set_value
    print(method())

c = Celsius()
working2(c, c.to_fahrenheit, 373)