<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def is_in_interval(n, l, r, border = 'included'):
 """ Checks whether a number is inside the interval l, r. """

        if 'included' == border:
            return (n >= l) and (n <= r)
        elif 'excluded' == border:
            return (n > l) and (n < r)
        else:
            raise ValueError('borders must be either \'included\' or \'excluded\'')