refactor(ogc): colocate ChunkedCall contract

Keep the private fetch/finalize aliases and default finalizer adjacent to their sole consumer.

Author: thodson-usgs

dataretrieval/ogc/chunking.py

@@ -101,30 +101,6 @@
     _retry,
 )
 
-# ---------------------------------------------------------------------------
-# Type aliases for the ChunkedCall contract.
-# ---------------------------------------------------------------------------
-
-# The per-sub-request fetcher the decorator wraps and ``ChunkedCall`` drives:
-# an ``async def fetch(args) -> (df, response)``.
-_Fetch = Callable[[dict[str, Any]], Awaitable[tuple[pd.DataFrame, httpx.Response]]]
-
-# Caller-supplied transform applied to the combined chunk result, so a
-# resumed call returns the same shape as an un-interrupted one rather than
-# the chunker's raw ``(frame, httpx.Response)``.  This keeps the chunker
-# generic: the OGC getters inject their post-processing (type coercion,
-# column arrangement, ``BaseMetadata``) through ``_finalize_ogc``.
-# The default is identity, so direct ``ChunkedCall`` use is unaffected.
-_Finalize = Callable[[pd.DataFrame, httpx.Response], tuple[pd.DataFrame, Any]]
-
-
-def _passthrough_result(
-    frame: pd.DataFrame, response: httpx.Response
-) -> tuple[pd.DataFrame, Any]:
-    """Default :data:`_Finalize`: return the raw combined pair unchanged."""
-    return frame, response
-
-
 # Empirically the API replies HTTP 414 above ~8200 bytes of full URL —
 # matches nginx's default ``large_client_header_buffers`` of 8 KB. 8000
 # leaves ~200 bytes for request-line framing and proxy variance. The decorator
@@ -312,6 +288,30 @@ def parallel_chunks(n: int) -> Iterator[None]:
         yield
 
 
+# ---------------------------------------------------------------------------
+# Type aliases for the ChunkedCall contract.
+# ---------------------------------------------------------------------------
+
+# The per-sub-request fetcher the decorator wraps and ``ChunkedCall`` drives:
+# an ``async def fetch(args) -> (df, response)``.
+_Fetch = Callable[[dict[str, Any]], Awaitable[tuple[pd.DataFrame, httpx.Response]]]
+
+# Caller-supplied transform applied to the combined chunk result, so a
+# resumed call returns the same shape as an un-interrupted one rather than
+# the chunker's raw ``(frame, httpx.Response)``.  This keeps the chunker
+# generic: the OGC getters inject their post-processing (type coercion,
+# column arrangement, ``BaseMetadata``) through ``_finalize_ogc``.
+# The default is identity, so direct ``ChunkedCall`` use is unaffected.
+_Finalize = Callable[[pd.DataFrame, httpx.Response], tuple[pd.DataFrame, Any]]
+
+
+def _passthrough_result(
+    frame: pd.DataFrame, response: httpx.Response
+) -> tuple[pd.DataFrame, Any]:
+    """Default :data:`_Finalize`: return the raw combined pair unchanged."""
+    return frame, response
+
+
 class ChunkedCall:
     """
     Stateful handle for a chunked call.