docs: def checkKey(self, key=None):
          '''
          Checks that an API key is valid.
  
          :param str key: (optional) A key that you want to check the validity of. Defaults to the one provided on initialization.
          :returns: If the key is valid, this method will return ``True``.
          :rtype: `bool`
          :raises: :class:`brickfront.errors.InvalidApiKey`
          '''
  
          # Get site
          url = Client.ENDPOINT.format('checkKey')
          if not key: key = self.apiKey
          params = {
              'apiKey': key or self.apiKey
          }
          returned = get(url, params=params)
          self.checkResponse(returned)
  
          # Parse and return
          root = ET.fromstring(returned.text)
          if root.text == 'OK':
              return True
          raise InvalidApiKey('The provided API key `{}` was invalid.'.format(key))