DOC: updated docstring of merge_entities

src/caosdb/apiutils.py

@@ -680,6 +680,15 @@ def compare_entities(old_entity: Entity, new_entity: Entity):
 def merge_entities(entity_a: Entity, entity_b: Entity):
     """
     Merge entity_b into entity_a such that they have the same parents and properties.
+
+    datatype, unit, value, name and description will only be changed in entity_a if they
+    are None for entity_a and set for entity_b. If there is a corresponding value
+    for entity_a different from None a RuntimeError will be raised informing of an
+    unresolvable merge conflict.
+
+    The merge operation is done in place.
+
+    Returns entity_a.
     """
 
     # Compare both entities: