code: def find_existing_items(
  	src, dst, *, fields=None, field_map=None,
  	normalize_values=False, normalize_func=normalize_value):
  	
  
  	if field_map is None:
  		field_map = FIELD_MAP
  
  	dst_keys = {
  		_gather_field_values(
  			dst_item, fields=fields, field_map=field_map,
  			normalize_values=normalize_values, normalize_func=normalize_func
  		) for dst_item in dst
  	}
  
  	for src_item in src:
  		if _gather_field_values(
  			src_item, fields=fields, field_map=field_map,
  			normalize_values=normalize_values, normalize_func=normalize_func
  		) in dst_keys:
  			yield src_item
docs: Find items from an item collection that are in another item collection.
  
  	Parameters:
  		src (list): A list of item dicts or filepaths.
  		dst (list): A list of item dicts or filepaths.
  		fields (list): A list of fields used to compare item dicts.
  		field_map (~collections.abc.Mapping): A mapping field name aliases.
  			Default: :data:`~google_music_utils.constants.FIELD_MAP`
  		normalize_values (bool): Normalize metadata values to remove common differences between sources.
  			Default: ``False``
  		normalize_func (function): Function to apply to metadata values if
  			``normalize_values`` is ``True``.
  			Default: :func:`~google_music_utils.utils.normalize_value`
  
  	Yields:
  		dict: The next item from ``src`` collection in ``dst`` collection.