Verify the compatibility of the tasks within a pipeline, especially with respect to task order. It is important to ensure that the assumptions of one task have not been violated by upstream processing; for example, UNOISE denoising employs a model of error rates in Illumina sequencing, and if errors have been removed by prior length or frequency filtering this model may not accurately fit to the data. Further, linked processes should be compatible: for instance, if OTU delimitation is based on a linkage algorithm such as swarm (Mahé et al., 2015), it is inappropriate to employ a simple similarity-based mapping method to assign reads to the resultant OTUs.