def check_n(seq):
    """
    Calculates N content of sequences. Returns 0 if N content is less than 5%
    and 1 if it is above 5%
    """
    n = 0
    for i in seq:
        if i == 'N':
            n += 1
    if n/len(seq) < 0.05:
        return 0
    else:
        return 1