code: def _prepend_name_prefix(self, name):
          
          if not self.name_prefix:
              return name
          base = self.name_prefix
          if base[0] != '/':
              base = '/' + base
          if name[0] != '/':
              name = '/' + name
          return base + name
docs: Return file name (ie. path) with the prefix directory prepended