def do_use(self, arg):
        """
        ::
        
            USAGE:

                use list           lists the available scopes

                use add SCOPE      adds a scope <scope>

                use delete SCOPE   removes the <scope>

                use                without parameters allows an
                                   interactive selection

            DESCRIPTION
               Often we have to type in a command multiple times. To save
               us typng the name of the command, we have defined a simple
               scope that can be activated with the use command

            ARGUMENTS:
                list         list the available scopes
                add          add a scope with a name
                delete       delete a named scope
                use          activate a scope

            """
        if arg == 'list':
            self._list_scope()
            return
        elif arg.startswith('add'):
            new_scope = arg.split(' ')[1]
            self._add_scope(new_scope)
            return
        elif arg.startswith('delete'):
            # delete does not work
            which_scope = arg.split(' ')[1]
            self._delete_scope(which_scope)
            return
        elif arg == "cm" or arg == "/":
            self.active_scope = ""
        elif arg in self.scopes:
            self.active_scope = arg
        else:
            self.active_scope = self.select(
                [""] + self.scopes, 'Which scope? ')

        if self.active_scope == "":
            Console.ok("Switched scope to: cm")
            self.prompt = self.active_scope + 'cm> '
        else:
            Console.ok("Switched scope to: {0}".format(self.active_scope))
            self.prompt = self.active_scope + '> '
::
        
            USAGE:

                use list           lists the available scopes

                use add SCOPE      adds a scope <scope>

                use delete SCOPE   removes the <scope>

                use                without parameters allows an
                                   interactive selection

            DESCRIPTION
               Often we have to type in a command multiple times. To save
               us typng the name of the command, we have defined a simple
               scope that can be activated with the use command

            ARGUMENTS:
                list         list the available scopes
                add          add a scope with a name
                delete       delete a named scope
                use          activate a scope