old_contents: from probfit.pdf import exponential
  from probfit.plotting import draw_pdf
  import matplotlib.pyplot as plt
  
  _arg = {"lambda": 0.5}
  draw_pdf(exponential, arg=_arg, bound=(0, 5), label=str(_arg), density=False,
           bins=100)
  
  arg = {"lambda": 1.0}
  draw_pdf(exponential, arg=_arg, bound=(0, 5), label=str(_arg), density=False,
           bins=100)
  
  arg = {"lambda": 1.5}
  draw_pdf(exponential, arg=_arg, bound=(0, 5), label=str(_arg), density=False,
           bins=100)
  
  plt.grid(True)
  plt.legend().get_frame().set_alpha(0.5)
  
new_contents: from probfit.pdf import exponential
  from probfit.plotting import draw_pdf
  import matplotlib.pyplot as plt
  
  _arg = {"lambda": 0.5}
  draw_pdf(exponential, arg=_arg, bound=(0, 5), label=str(_arg), density=False,
           bins=100)
  
  _arg = {"lambda": 1.0}
  draw_pdf(exponential, arg=_arg, bound=(0, 5), label=str(_arg), density=False,
           bins=100)
  
  _arg = {"lambda": 1.5}
  draw_pdf(exponential, arg=_arg, bound=(0, 5), label=str(_arg), density=False,
           bins=100)
  
  plt.grid(True)
  plt.legend().get_frame().set_alpha(0.5)
  
subject: replace arg to _arg in doct/pyplots/pdf/exponential.py