def cov_files_by_platform(reads, assembly, platform):
    """
    Return a list of coverage files for a given sequencing platform.
    """
    accessions = []
    if reads is not None:
        accessions += [accession for accession in reads if reads[accession]['platform'] == platform]
    return list(map(lambda sra: "%s.%s.bam.cov" % (assembly, sra), accessions))