Newton's Method implemented in Python

newton.py

def newton(x0, f, f_, n = 1, r=7):
    for i in range(n):
        xi = x0 - (f(x0) / f_(x0))
        print(f'x{i+1} =', round(xi, r))
        x0 = xi

"""
Works for arbitrarily precise floating points.

Usage - calculating √169 (13).

def f(x):
    return x**2 - 169

def f_(x):
    return 2*x

newton(12, f, f_, 5, 7)
"""