def graph_key_from_tag(tag, entity_index):
start_token = tag.get('<STR_LIT>')<EOL>entity = tag.get('<STR_LIT>', [])[entity_index]<EOL>return str(start_token) + '<STR_LIT:->' + entity.get('<STR_LIT:key>') + '<STR_LIT:->' + str(entity.get('<STR_LIT>'))<EOL>
Returns a key from a tag entity

    Args:
        tag (tag) : this is the tag selected to get the key from
        entity_index (int) : this is the index of the tagged entity

    Returns:
        str : String representing the key for the given tagged entity.