old_contents: """
  contacts.rules
  ~~~~~~~~~~~~
  This module sets rules for Contacts 📕.
  :copyright: (c) 2017 by David Heimann.
  :license: MIT, see LICENSE for more details.
  """
  
  
  ALLOWED_FIELDS = [
      'name',
      'first_name',
      'last_name',
      'phone_number',
      'photo',
      'email',
      'twitter'
  ]
new_contents: """
  contacts.rules
  ~~~~~~~~~~~~
  This module sets rules for Contacts 📕.
  :copyright: (c) 2017 by David Heimann.
  :license: MIT, see LICENSE for more details.
  """
  
  
  ALLOWED_FIELDS = [
      'name',
      'phone_number',
      'first_name',
      'last_name',
      'phone_number',
      'photo',
      'email',
      'twitter'
  ]
subject: Add 'phone_number' field to ALLOWED_FIELDS.