import matplotlib.pyplot as plt
import numpy as np
xs = np.linspace(0, np.pi, 50)
fig, ax = plt.subplots()
ys = 0
lbl=''
for n in [1, 3, 5]:
a = 1.0/n
ys = ys+a*np.sin(n*xs)
lbl = lbl + f"1/{n} sin({n}x)"
ax.plot(xs, ys, label=lbl)
lbl = lbl + '+' #why do we add the "+" at this point?
# set the legend and show the figure
ax.legend(loc=(1.01, 0))
fig.show()