Indexes can not work with negative values

The problem becomes visible if the `use_nodecache.py` example is run with an osm file that contains nodes with negative ints. ``` » ./use_nodecache.py map_minimal.osm cache Traceback (most recent call last): File "/osmgj/./use_nodecache.py", line 31, in <module> osmium.apply(reader, lh, WayHandler(idx)) File "/osmgj/./use_nodecache.py", line 17, in way locations.append(idx.get(n.ref)) # note that cache is used here ^^^^^^^^^^^^^^ TypeError: get(): incompatible function arguments. The following argument types are supported: 1. (self: osmium.index.LocationTable, id: int) -> osmium.osm._osm.Location Invoked with: <osmium.index.LocationTable object at 0x7f675e724170>, -138468 ``` When using a fix positive nonexistent id like 100 a `KeyError` is raised. To me it looks like the problem is here. The osmium lib uses unsigned integers and even ensures this with `enable_if`. ``` using LocationTable = osmium::index::map::Map<osmium::unsigned_object_id_type, osmium::Location>; using IndexFactory = osmium::index::MapFactory<osmium::unsigned_object_id_type, osmium::Location>; py::class_<LocationTable>(m, "LocationTable") .def("set", &LocationTable::set, py::arg("id"), py::arg("loc")) .def("get", &LocationTable::get, py::arg("id")) ``` ``` # Set up the OSM handler node_cache = UnsingedLocationTableWrapper(osmium.index.create_map('flex_mem')) handler_create_json = OSMHandler(node_cache) > handler_read_node_cache = osmium.NodeLocationsForWays(node_cache) E TypeError: __init__(): incompatible constructor arguments. The following argument types are supported: E 1. osmium._osmium.NodeLocationsForWays(arg0: osmium::index::map::Map<unsigned long, osmium::Location>) E E Invoked with: <osmgj.UnsingedLocationTableWrapper object at 0x7f2586e1da90> ``` I have tried to use a python wrapper, but at some points the c/c++ structs are expected and my wrapping code is not accepted. As Python only knows about ints and has not notion of unsigned and the osmium lib requires unsigned this library should do a conversion && check if the value is in the rage or raise a ValueError (too big/small). Or offer some other mechanic to allow the usage of negative integers.