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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def fake(args):
 """ %prog fake input.bed Make fake `scaffolds.fasta`. Use case for this is that sometimes I would receive just the csv/bed file and I'd like to use path() out of the box. """

    from math import ceil
    from random import choice

    from Bio import SeqIO
    from Bio.Seq import Seq
    from Bio.SeqRecord import SeqRecord

    p = OptionParser(fake.__doc__)
    p.set_outfile()
    opts, args = p.parse_args(args)

    if len(args) != 1:
        sys.exit(not p.print_help())

    inputbed, = args
    bed = Bed(inputbed)
    recs = []
    for seqid, sb in bed.sub_beds():
        maxend = max(x.end for x in sb)
        size = int(ceil(maxend / 1000.) * 1000)
        seq = "".join([choice("ACGT") for x in xrange(size)])
        rec = SeqRecord(Seq(seq), id=seqid, description="")
        recs.append(rec)

    fw = must_open(opts.outfile, "w")
    SeqIO.write(recs, fw, "fasta")