def __getitem__(key):
    """Return Browser request data

        Request data are retrieved from one of:

        - Environment variables

          These variables include input headers, server data, and other
          request-related data.  The variable names are as
          specified
          in the `CGI specification <https://tools.ietf.org/html/rfc3875>`_.

        - Cookies

          These are the cookie data, if present.

        - Form data

        Form data are searched before cookies, which are searched
        before environmental data.
        """
