def get_argument(self, name, default=_ARG_DEFAULT, strip=True):
        """Returns the value of the argument with the given name.

        If default is not provided, the argument is considered to be
        required, and we throw an HTTP 400 exception if it is missing.

        If the argument appears in the url more than once, we return the
        last value.

        The returned value is always unicode.
        """
        args = self.get_arguments(name, strip=strip)
        if not args:
            if default is self._ARG_DEFAULT:
                raise HTTPError(400, "Missing argument %s" % name)
            return default
        return args[-1]
Returns the value of the argument with the given name.

        If default is not provided, the argument is considered to be
        required, and we throw an HTTP 400 exception if it is missing.

        If the argument appears in the url more than once, we return the
        last value.

        The returned value is always unicode.