text: import numpy as np
  import pymc as pm
  from ch1 import count_data
  from IPython.core.pylabtools import figsize
  import matplotlib.pyplot as plt
  plt.style.use('ggplot')
  
  plt.hist(count_data, bins = 20)
  plt.xlabel('text messages per day')
  plt.ylabel('frequency')
  plt.show()