If I understand the API correctly from my brief glance, the crate returns a triply-nested vector with the outermost vector being the equivalent of CSV rows, then CSV columns, then "units" which don't have a direct CSV equivalent. It would be helpful if there was an API method that returned results without this final level of nesting, perhaps panicking if there is more than one unit. This would make it easier to deal with the common case (in CSV at least) where each column only has a single value.