code: def get_email_regex(self):
          
          validator = self.default_validators[0]
          user_regex = validator.user_regex.pattern.replace('\Z', '@')
          domain_patterns = ([re.escape(domain) + '$' for domain in
                              validator.domain_whitelist] +
                             [validator.domain_regex.pattern.replace('\Z', '$')])
          domain_regex = '({0})'.format('|'.join(domain_patterns))
          email_regex = user_regex + domain_regex
          return re.sub(r'\(\?\<[^()]*?\)', '', email_regex)
docs: Return a regex pattern matching valid email addresses. Uses the same
          logic as the django validator, with the folowing exceptions:
  
          - Internationalized domain names not supported
          - IP addresses not supported
          - Strips lookbehinds (not supported in javascript regular expressions)