from probfit.pdf import doublecrystalball
from probfit.plotting import draw_normed_pdf
import matplotlib.pyplot as plt

bound = (5.22, 5.30)

arg = dict(alpha=1.,alpha2=1., n=2.,n2=2, mean=5.28, sigma=0.01)
draw_normed_pdf(crystalball, arg=arg, bound=bound, label=str(arg), density=True)

arg = dict(alpha=0.5, alpha2=0.5, n=10., n2=10., mean=5.28, sigma=0.005)
draw_normed_pdf(crystalball, arg=arg, bound=bound, label=str(arg), density=True)

plt.grid(True)
plt.legend().get_frame().set_alpha(0.5)

Create doublecrystalball.py