>>> class F:
...     def __init__(self, cost, value):
...         self.cost = cost
...         self.value = value
...     def getValueDividedByCost(self):
...         return self.value / self.cost

>>> superfood = F(0.1, 1000)

>>> superfood.cost
0.1

>>> superfood.value  # so both of these are data attributes
1000

>>> superfood.getValueDividedByCost()  # this is calling a function (method)
10000.0

>>>