def plot_hist(x, p=5):
 # Plot the distribution and mark the mean
 plt.hist(x, alpha=.5)
 plt.axvline(x.mean())
 # 95% confidence interval 
 plt.axvline(np.percentile(x, p/2.), color='red', linewidth=3)
 plt.axvline(np.percentile(x, 100-p/2.), color='red', linewidth=3)

def plot_dists(a, b, nbins, a_label='pop_A', b_label='pop_B', p=5):
 # Create a single sequence of bins to be shared across both
 # distribution plots for visualization consistency.
 combined = pd.concat([a, b])
 breaks = np.linspace(
 combined.min(), 
 combined.max(), 
 num=nbins+1)