text: import matplotlib
  import matplotlib.pyplot as plt
  
  import json
  import glob
  import sys
  from dateutil.parser import isoparse
  
  json_files = glob.glob('data/*.json')
  
  f, ax = plt.subplots(1, len(json_files), sharey=True, figsize=(20, 8))
  
  font = {'size'   : 12}
  matplotlib.rc('font', **font)
  
  for i, fn in enumerate(json_files):
      data = json.load(open(fn, 'r'))
  
      prs_unknown = [p for p in data if p['mergeable'] == 'UNKNOWN']
      if len(prs_unknown) != 0:
          print('Found PRs with unknown merge status.  Please redownload data.')
          sys.exit(-1)
  
      prs_conflicting = [isoparse(p['createdAt']) for p in data if p['mergeable'] == 'CONFLICTING']
      prs_other = [isoparse(p['createdAt']) for p in data if p['mergeable'] == 'MERGEABLE']
      ax[i].hist(
          [prs_conflicting, prs_other],
          bins='auto',
          histtype='bar',
          label=('conflicting', 'other'),
          color=('red', 'blue')
      )
      ax[i].set_title('/'.join(fn.replace('.json', '').split('__')))
      ax[i].set_xlabel('PR number')
      ax[i].legend()
      if i == 0:
          ax[i].set_ylabel('Number of conflicting PRs')
  
  plt.tight_layout()
  plt.savefig('pr-hist.png', dpi=300, )
  plt.show()
  