python import numpy as np from scipy import signal t = np.linspace(0, 1, 1000) x = np.sin(2*np.pi*10*t) + np.sin(2*np.pi*20*t) order = 4 cutoff_freq = 15 filtered_x = signal.lfilter(b, a, x) import matplotlib.pyplot as plt plt.legend() plt.show()