number, start be an index, ��� be a list of integers, and result be a list of lists. a ) Explain what the Mystery function does. b ) Find an upper bound for its time complexity (   ���   ) . Hint: You need to write ��� ( ��� , ��� ) as a recurrence relation and solve it by expanding it . function func ( ��� , ��� ) : A . sort (   ) result = [ ] Mystery ( A , x ,   0 , [ ] , result ) return result function Mystery (   ��� , ��� , start, ��� , result ) : if ��� = 0 : result. append (   ��� return if ��� < 0 : return for i from start to ���   -   1 : , result )