[python] Expose tiledbsoma.io.ExperimentAmbientLabelMapping (#2175)

* [python] Expose tiledbsoma.io.ExperimentAmbientLabelMapping

* protect

* code-review feedback

apis/python/src/tiledbsoma/io/__init__.py

@@ -1,3 +1,6 @@
+from ._registration import (
+    ExperimentAmbientLabelMapping,
+)
 from .ingest import (
     add_matrix_to_collection,
     add_X_layer,
@@ -32,4 +35,5 @@
     "update_matrix",
     "update_obs",
     "update_var",
+    "ExperimentAmbientLabelMapping",
 )

apis/python/tests/test_registration_mappings.py

@@ -1094,3 +1094,11 @@ def test_registration_with_batched_reads(tmp_path, soma_larger, use_small_buffer
     )
 
     assert len(rd.obs_axis.data) == 1000
+
+
+def test_ealm_expose():
+    """Checks that this is exported from tiledbsoma.io._registration"""
+    # All we want to check is that the import doesn't throw. Job done. Period.
+    # However, the pre-commit hook will strip out this import statement as "unused".
+    # So, assert something.
+    assert tiledbsoma.io.ExperimentAmbientLabelMapping is not None