flatten accepts mixing of lists and non-lists
flatten accepts mixing of lists and non-lists

PhE/dask,PeterDSteinberg/dask,hainm/dask,chrisbarber/dask,minrk/dask,blaze/dask,wiso/dask,jayhetee/dask,mraspaud/dask,clarkfitzg/dask,PhE/dask,jakirkham/dask,esc/dask,pombredanne/dask,blaze/dask,gameduell/dask,marianotepper/dask,vikhyat/dask,mrocklin/dask,simudream/dask,simudream/dask,hainm/dask,freeman-lab/dask,ssanderson/dask,mraspaud/dask,dask/dask,freeman-lab/dask,minrk/dask,cowlicks/dask,jcrist/dask,ssanderson/dask,marianotepper/dask,vikhyat/dask,jayhetee/dask,cpcloud/dask,wiso/dask,clarkfitzg/dask,mrocklin/dask,jakirkham/dask,jcrist/dask,esc/dask,ContinuumIO/dask,ContinuumIO/dask,mikegraham/dask,pombredanne/dask,dask/dask