Use of matplotlib module for graph in python

Python code
import numpy as np
import matplotlib.pyplot as plt
plt.axis([-75,75,50,-50])
plt.axis('on')
plt.grid(True)
plt.arrow(0,0,20,0,head_length=4,head_width=3,color='k')
plt.arrow(0,0,0,20,head_length=4,head_width=3,color='k')
plt.text(-60,-60,'Learn Python in Dnyandeep-1')
plt.text(-60,40,'Use of matplotlib and numpy for co-ordinate Geometry')
plt.text(-60,-45,'Drawing Rectangle on Graph')
plt.text(22,-3,'x')
plt.text(-5,25,'y')
#—————————————————red box
plt.plot([-20,20],[-20,-20],linewidth=2,color='r')
plt.plot([20,20],[-20,20],linewidth=2,color='r')
plt.plot([20,-20],[20,20],linewidth=2,color='r')
plt.plot([-20,-20],[-20,20],linewidth=2,color='r')
#——————————————green list box
x=[-30,30,30,-30,-30]
y=[-30,-30,30,30,-30]
plt.plot(x,y,linewidth=2,color='g')
plt.show()

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Output