code: def GC_wide(genome, window=1000):
      
  
      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
docs: Compute GC across a window of given length.
  
      :note: Requires Biopython