text: import re
  import sys
  
  import logging
  logging.basicConfig(level=logging.DEBUG)
  
  logger = logging.getLogger('pre_gen_project')
  
  APP_REGEX = r'^[_a-zA-Z][_a-zA-Z0-9]+$'
  
  app_name = '{{cookiecutter.app_name}}'
  
  if not re.match(APP_REGEX, app_name):
      logger.error('Invalid value for app_name "{}". Invalid characters found.'.format(app_name))
      sys.exit(1)
  