Added --post-function to import, #842 (#851)

examples/post_function_import.py

@@ -0,0 +1,28 @@
+""" Example function for use with osxphotos import --post-function option """
+
+import typing as t
+import photoscript
+import pathlib
+
+def post_function(
+    photo: photoscript.Photo, filepath: pathlib.Path, verbose: t.Callable, **kwargs
+):
+    """Call this with osxphotos import /file/to/import --post-function post_function.py::post_function
+        This will get called immediately after the photo has been imported into Photos
+        and all metadata been set (e.g. --exiftool, --title, etc.)
+
+    Args:
+        photo: photoscript.Photo instance for the photo that's just been imported
+        filepath: pathlib.Path to the file that was imported (this is the path to the source file, not the path inside the Photos library)
+        verbose: A function to print verbose output if --verbose is set; if --verbose is not set, acts as a no-op (nothing gets printed)
+        **kwargs: reserved for future use; recommend you include **kwargs so your function still works if additional arguments are added in future versions
+
+    Notes:
+        Use verbose(str) instead of print if you want your function to conditionally output text depending on --verbose flag
+        Any string printed with verbose that contains "warning" or "error" (case-insensitive) will be printed with the appropriate warning or error color
+        See https://rhettbull.github.io/PhotoScript/ for documentation on photoscript
+    """
+
+    # add a note to the photo's description
+    verbose("Adding note to description")
+    photo.description = f"{photo.description} (imported with osxphotos)"