# `write_by_region` writes chunk-wise data into an initialized dataset in swift.
# 'Initiliazed' means that a first `to_zarr` call has been executed which writes all coordinates and metadata for the dataset into the chunk. The subsequent `to_zarr` calls performed by `write_to_region` uses this information so that it knows how chunks have to be named. If a region has already been written, it will be overwritten by write_to_region.