Encapsulation

Sometimes the use of inheritance is impractical or even impossible. This motivates the use of encapsulation. We will explain the concept of encapsulation by considering Python functions, that is, objects of the Python type function, which we encapsulate in a new class, Function, and provide with some relevant methods:

class Function:
    def __init__(self, f):
        self.f = f
    def __call__(self, x):
        return self.f(x)
    def __add__(self, g):
        def sum(x):
            return self(x) + g(x)
        return type(self)(sum) 
    def __mul__(self, g): 
        def prod(x):
            return self.f(x) * g(x)
        return type(self)(prod...