Fixed template function to work with import command (#765)

examples/template_function_import.py

@@ -0,0 +1,27 @@
+""" Example showing how to use a custom function for osxphotos {function} template with the `osxphotos import` command 
+    Use:  osxphotos import /path/to/import/*.jpg --album "{function:/path/to/template_function_import.py::example}"
+
+    You may place more than one template function in a single file as each is called by name using the {function:file.py::function_name} format
+"""
+
+import pathlib
+from typing import List, Optional, Union
+
+
+def example(
+    filepath: pathlib.Path, args: Optional[str] = None, **kwargs
+) -> Union[List, str]:
+    """example function for {function} template for use with `osxphotos import`
+
+    This example parses filenames in format album_img_123.jpg and returns the album name
+
+    Args:
+        filepath: pathlib.Path object of file being imported
+        args: optional str of arguments passed to template function
+        **kwargs: not currently used, placeholder to keep functions compatible with possible changes to {function}
+    Returns:
+        str or list of str of values that should be substituted for the {function} template
+    """
+    filename = filepath.stem
+    fields = filename.split("_")
+    return fields[0] if len(fields) > 1 else ""