def GC_wide(genome, window=1000):
    """Compute GC across a window of given length.

    :note: Requires Biopython
    """

    GC = []
    from Bio import SeqIO
    with open(genome) as handle:
        sequence = "".join([str(record.seq)
                            for record in SeqIO.parse(handle, "fasta")])

    n = len(sequence)
    for i in range(0, n, window):
        portion = sequence[i:min(i + window, n)]
        GC.append(GC_partial(portion))

    return GC