import numpy as np
import matplotlib.pyplot as plt
from pylab import legend

x = np.linspace(1,10, 100)
y = x**3

fig = plt.figure()
ax = fig.add_subplot(1,1,1)
ax.plot(x,y, 'bo', label='Blah!')
lg = legend(numpoints = 1, loc=2)
lg.get_frame().set_alpha(0)
#ax.legend(numpoints = 1, loc=2)

plt.show()