Many (most?) bioinformatics tools are built to read and write to a local filesystem. For example: read a "fastq" file along with some extra reference datafiles and write out a "bam" file, all to local disk. How would this be encoded as an op? Take a set of paths as input and return a set of paths as output? Would you then rely on an IOManager to bring the files from S3 to local disk and back?