code: def get_within_delta(self, key):
          
          txt = current_app.config.get(key)
          values = txt.split()
          return timedelta(**{values[1]: int(values[0])})
docs: Get a timedelta object from the application configuration following
          the internal convention of::
  
              <Amount of Units> <Type of Units>
  
          Examples of valid config values::
  
              5 days
              10 minutes
  
          :param key: The config value key