# %% Import of e.g. numpy placed here if needed

# import numpy as np

# %% Defintion of class Formula_1:

class Formula_1(object):
    
    def __init__(self, c0, c1):
        self.c0 = c0
        self.c1 = c1
        
    def output(self, x):
        c0 = self.c0
        c1 = self.c1
        y = c1*x + c0
        return y
        
    def rate(self):
        r = self.c1
        return r


class Formula_2(Formula_1):
    
    def __init__(self, c0, c1, c2):
        Formula_1.__init__(self, c0, c1)
        self.c2 = c2
        
    def output(self, x):
        y1 = Formula_1.output(self, x) 
        y2 = self.c2*x**2 + y1
        return y2


class Formula_3(Formula_2):
    
    def __init__(self, c0, c1, c2, c3):
        Formula_2.__init__(self, c0, c1, c2)
        self.c3 = c3
        
    def output(self, x):
        y2 = Formula_2.output(self, x) 
        y3 = self.c3*x**3 + y2
        return y3

# %% Application of class Formula_1:

# Defining variables used in calling instance F3:
k0 = 0
k1 = 1
k2 = 2
k3 = 3
x = 5

# Creating instance here named F3:
F3 = Formula_3(k0, k1, k2, k3)

# Calling method named output of F3:
print('y3 = output value of F3:', F3.output(x))