Add example to getGuid doc string

Author: JonnyWong16

plexapi/library.py

@@ -465,14 +465,32 @@ def get(self, title):
 
     def getGuid(self, guid):
         """ Returns the media item with the specified external IMDB, TMDB, or TVDB ID.
-            Note: This search uses a PlexAPI operator so performance may be slow.
+            Note: This search uses a PlexAPI operator so performance may be slow. All items from the
+            entire Plex library need to be retrieved for each guid search. It is recommended to create
+            your own lookup dictionary if you are searching for a lot of external guids.
 
             Parameters:
                 guid (str): The external guid of the item to return.
                     Examples: IMDB ``imdb://tt0944947``, TMDB ``tmdb://1399``, TVDB ``tvdb://121361``.
 
             Raises:
                 :exc:`~plexapi.exceptions.NotFound`: The guid is not found in the library.
+
+            Example:
+
+                .. code-block:: python
+
+                    # This will retrieve all items in the entire library 3 times
+                    result1 = library.getGuid('imdb://tt0944947')
+                    result2 = library.getGuid('tmdb://1399')
+                    result3 = library.getGuid('tvdb://121361')
+
+                    # This will only retrieve all items in the library once to create a lookup dictionary
+                    guidLookup = {guid.id: item for item in library.all() for guid in item.guids}
+                    result1 = guidLookup['imdb://tt0944947']
+                    result2 = guidLookup['tmdb://1399']
+                    result3 = guidLookup['tvdb://121361']
+
         """
         key = '/library/sections/%s/all?includeGuids=1' % self.key
         return self.fetchItem(key, Guid__id__iexact=guid)