code: def get_as_list(self, tag_name):
          
          val = self.get(tag_name, [])
          if isinstance(val, list):
              return val[:]
          else:
              return [val]
docs: Return the value of a tag, making sure that it's a list.  Absent
          tags are returned as an empty-list; single tags are returned as a
          one-element list.
  
          The returned list is a copy, and modifications do not affect the
          original object.