returns the specified connection

        args:
            conn_name: the name of the connection

def get(self, conn_name, default=None, **kwargs):
        """ returns the specified connection

        args:
            conn_name: the name of the connection
        """

        if isinstance(conn_name, RdfwConnections):
            return conn_name
        try:
            return self.conns[conn_name]
        except KeyError:
            if default:
                return self.get(default, **kwargs)
            raise LookupError("'%s' connection has not been set" % conn_name)