avoid lambdas including self in cumulative aggregates
avoid lambdas including self in cumulative aggregates

cowlicks/dask,mikegraham/dask,blaze/dask,gameduell/dask,ContinuumIO/dask,jcrist/dask,jakirkham/dask,mrocklin/dask,mraspaud/dask,mrocklin/dask,ContinuumIO/dask,dask/dask,cpcloud/dask,blaze/dask,jcrist/dask,mraspaud/dask,jakirkham/dask,chrisbarber/dask,dask/dask