'Prompt for a redirect value and set it in Truantchild'

def prompt_redir(self, plugin, var, msg, default):

    done = None
    while (not done):
        try:
            line = self.io.prompt_user(msg, default)
            plugin.set(var, line)
            done = plugin.hasValidValue(var)
        except exception.PromptHelp as err:
            self.io.print_warning('No    help    available')
        except exception.PromptErr as err:
            raise
        except exception.CmdErr as err:
            self.io.print_error(err.getErr())
    return plugin.get(var)
