Matplotlib.axes.Axes.legend() in Python

# Implementation of matplotlib function
import matplotlib.pyplot as plt
fig, ax = plt.subplots()
line1, = ax.plot([1, 2, 3],
                 label ="Line 1",
                 color ="black", 
                 linewidth = 4,
                 linestyle =':')
line2, = ax.plot([3, 2, 1], 
                 label ="Line 2",
                 color ="green", 
                 linewidth = 4)
first_legend = ax.legend(handles =[line1], 
                         loc ='upper center')
ax.add_artist(first_legend)
ax.legend(handles =[line2], loc ='lower center')
fig.suptitle('matplotlib.axes.Axes.legend() \
function Example\n', fontweight ="bold")
plt.show()

# Implementation of matplotlib function
import numpy as np
import matplotlib.pyplot as plt
np.random.seed(19680801)
fig, ax = plt.subplots()
for color in [ 'tab:green', 'tab:blue',
               'tab:orange']:
    n = 70
    x, y = np.random.rand(2, n)
    scale = 1000.0 * np.random.rand(n)
    ax.scatter(x, y, c = color, s = scale,
               label = color,
               alpha = 0.35)
ax.legend()
ax.grid(True)
fig.suptitle('matplotlib.axes.Axes.legend() function\
 Example\n', fontweight ="bold")
plt.show()