code: def test_dict_subclass(tmpdir):
      """Rasterio now has a `CRS()` class that subclasses
      `collections.UserDict()`.  Make sure we can receive it.
  
      `UserDict()` is a good class to test against because in Python 2 it is
      not a subclass of `collections.Mapping()`, so it provides an edge case.
      """
  
      class CRS(UserDict):
          pass
  
      outfile = str(tmpdir.join("test_UserDict.geojson"))
  
      profile = {
          "crs": CRS(init="EPSG:4326"),
          "driver": "GeoJSON",
          "schema": {"geometry": "Point", "properties": {}},
      }
  
      with fiona.open(outfile, "w", **profile) as dst:
          dst.write(
              Feature.from_dict(
                  **{
                      "type": "Feature",
                      "properties": {},
                      "geometry": {
                          "type": "Point",
                          "coordinates": (10, -10),
                      },
                  }
              )
          )
  
      with fiona.open(outfile) as src:
          assert len(src) == 1
          assert src.crs == {"init": "epsg:4326"}
  
imports: from collections import UserDict
  import fiona
  from fiona.model import Feature
label_desc: Use image node_id 1 for calling a global function with example usage: test_dict_subclass(tmpdir) without return types