def iterator_contigs( gffs ):

    last_contig, data = None, []
    found = set()
    for gff in gffs:
        if last_contig != gff.contig:
            if last_contig: yield last_contig, data
            last_contig = gff.contig
            assert last_contig not in found, "input not sorted by contig."
            found.add(last_contig) 

        data.append( gff )

    if last_contig: yield last_contig, data
Given the conditional parameters, computes the log-conditional
dataset/ETHPy150Open CGATOxford/cgat/obsolete/GFF.py/iterator_contigs--crossover with--dataset/ETHPy150Open lisa-lab/pylearn2/pylearn2/models/vae/conditional.py/Conditional.log_conditional