old_contents: import os
  import re
  import shutil
  import requests
  import json
  try:
      from StringIO import StringIO
  except ModuleNotFoundError:  # py3 workaround
      from io import BytesIO as StringIO
  
  # Info taken from https://caniuse.com/#feat=variable-fonts
  MIN_VF_BROWSERS = {
      'chrome': 67,
      'firefox': 62,
      'edge': 17,
      'safari': 11,
  }
  
  
  def browser_supports_vfs(user_agent):
      """Check if the user's browser supports variable fonts
  
      Parameters
      ----------
      user_agent: werkzeug.useragents.UserAgent
  
      Returns
      -------
      Boolean"""
      user_browser = user_agent.browser
      browser_version = int(user_agent.version.split('.')[0])
      if browser_version < MIN_VF_BROWSERS[user_browser]:
          return False
      return True
  
  
  def download_file(url, dst_path=None):
      """Download a file from a url. If no url is specified, store the file
      as a StringIO object"""
      request = requests.get(url, stream=True)
      if not dst_path:
          return StringIO(request.content)
      with open(dst_path, 'wb') as downloaded_file:
          shutil.copyfileobj(request.raw, downloaded_file)
  
  
  def filename_to_family_name(path):
      '''Convert a fontpath into a font name.
      /path/to/SomeSans-Regular.ttf --> Some Sans'''
      filename = os.path.basename(path)[:-4]
      family = filename.split('-')[0]
      family = _convert_camelcase(family)
      return family
  
  
  def _convert_camelcase(fam_name, seperator=' '):
      '''RubikMonoOne > Rubik Mono One'''
      if fam_name not in FONT_EXCEPTIONS:
          return re.sub('(?!^)([A-Z]|[0-9]+)', r'%s\1' % seperator, fam_name)
      else:
          fam_name = FONT_EXCEPTIONS[fam_name].replace(' ', seperator)
          return fam_name
  
  
  with open("secrets.json") as f:
      secrets = json.loads(f.read())
  
  def secret(key, secret=secrets):
      try:
          return secret[key]
      except KeyError:
          raise Exception('Secret {} does not exist'.format(secret))
  
new_contents: import os
  import re
  import shutil
  import requests
  import json
  try:
      from StringIO import StringIO
  except ModuleNotFoundError:  # py3 workaround
      from io import BytesIO as StringIO
  
  # Info taken from https://caniuse.com/#feat=variable-fonts
  MIN_VF_BROWSERS = {
      'chrome': 67,
      'firefox': 62,
      'edge': 17,
      'safari': 11,
  }
  
  
  def browser_supports_vfs(user_agent):
      """Check if the user's browser supports variable fonts
  
      Parameters
      ----------
      user_agent: werkzeug.useragents.UserAgent
  
      Returns
      -------
      Boolean"""
      user_browser = user_agent.browser
      browser_version = int(user_agent.version.split('.')[0])
      if user_browser not in MIN_VF_BROWSERS:
          return False
      if browser_version < MIN_VF_BROWSERS[user_browser]:
          return False
      return True
  
  
  def download_file(url, dst_path=None):
      """Download a file from a url. If no url is specified, store the file
      as a StringIO object"""
      request = requests.get(url, stream=True)
      if not dst_path:
          return StringIO(request.content)
      with open(dst_path, 'wb') as downloaded_file:
          shutil.copyfileobj(request.raw, downloaded_file)
  
  
  def filename_to_family_name(path):
      '''Convert a fontpath into a font name.
      /path/to/SomeSans-Regular.ttf --> Some Sans'''
      filename = os.path.basename(path)[:-4]
      family = filename.split('-')[0]
      family = _convert_camelcase(family)
      return family
  
  
  def _convert_camelcase(fam_name, seperator=' '):
      '''RubikMonoOne > Rubik Mono One'''
      if fam_name not in FONT_EXCEPTIONS:
          return re.sub('(?!^)([A-Z]|[0-9]+)', r'%s\1' % seperator, fam_name)
      else:
          fam_name = FONT_EXCEPTIONS[fam_name].replace(' ', seperator)
          return fam_name
  
  
  with open("secrets.json") as f:
      secrets = json.loads(f.read())
  
  def secret(key, secret=secrets):
      try:
          return secret[key]
      except KeyError:
          raise Exception('Secret {} does not exist'.format(secret))
  
subject: Raise exception if diff is for VFs and browser used is not in MIN_VF_BROWSERS