docs: def _get_endpoint(self, sub_domain):
          """
          Get endpoint information from storage parameters.
  
          Update system with endpoint information and return information required
          to define roots.
  
          Args:
              self (pycosio._core.io_system.SystemBase subclass): System.
              sub_domain (str): Azure storage sub-domain.
  
          Returns:
              tuple of str: account_name, endpoint_suffix
          """
          storage_parameters = self._storage_parameters or dict()
          account_name = storage_parameters.get('account_name')
  
          if not account_name:
              raise ValueError('"account_name" is required for Azure storage')
  
          suffix = storage_parameters.get(
              'endpoint_suffix', 'core.windows.net')
  
          self._endpoint = 'http%s://%s.%s.%s' % (
              '' if self._unsecure else 's', account_name, sub_domain, suffix)
  
          return account_name, suffix.replace('.', r'\.')