update tokenize docstring
update tokenize docstring

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