docs: update api-completeness with duckdb (#1740)

docs/basics/dataframe_conversion.md

@@ -53,7 +53,9 @@ which implements `__arrow_c_stream__`:
 def df_to_polars(df_native: Any) -> pl.DataFrame:
     if hasattr(df_native, "__arrow_c_stream__"):
         return nw.from_arrow(df_native, native_namespace=pl).to_native()
-    msg = f"Expected object which implements '__arrow_c_stream__' got: {type(df)}"
+    msg = (
+        f"Expected object which implements '__arrow_c_stream__' got: {type(df_native)}"
+    )
     raise TypeError(msg)
 
 

utils/generate_backend_completeness.py

@@ -31,9 +31,10 @@ class Backend(NamedTuple):
 MODULES = ["dataframe", "series", "expr"]
 
 BACKENDS = [
-    Backend(name="pandas-like", module="_pandas_like", type_=BackendType.EAGER),
     Backend(name="arrow", module="_arrow", type_=BackendType.EAGER),
     Backend(name="dask", module="_dask", type_=BackendType.LAZY),
+    Backend(name="duckdb", module="_duckdb", type_=BackendType.LAZY),
+    Backend(name="pandas-like", module="_pandas_like", type_=BackendType.EAGER),
     Backend(name="spark-like", module="_spark_like", type_=BackendType.LAZY),
 ]
 
@@ -55,6 +56,7 @@ def parse_module(module_name: str, backend: str, nw_class_name: str) -> list[str
                 inspect.isclass(c)
                 and c.__name__.endswith(nw_class_name)
                 and not c.__name__.startswith("Compliant")  # Exclude protocols
+                and not c.__name__.startswith("DuckDBInterchange")
             ),
         )