Fixed bug in query.py where 0 was not being taken as a valid index

        exit()

    # checking valid index

    if not index:

        print('Please enter a valid index.')

        exit()

    if any(index < 0 or index > len(seq) for seq in sequence.split(',')):

        print(f'The provided index {index} is outside of the possible range of {sequence}. The first position of the index is 0.')

        exit()