code: def cfg_convert(self, value):
          
          rest = value
          m = self.WORD_PATTERN.match(rest)
          if m is None:
              raise ValueError("Unable to convert %r" % value)
          else:
              rest = rest[m.end():]
              d = self.config[m.groups()[0]]
              # print d, rest
              while rest:
                  m = self.DOT_PATTERN.match(rest)
                  if m:
                      d = d[m.groups()[0]]
                  else:
                      m = self.INDEX_PATTERN.match(rest)
                      if m:
                          idx = m.groups()[0]
                          if not self.DIGIT_PATTERN.match(idx):
                              d = d[idx]
                          else:
                              try:
                                  n = int(idx)
                                  d = d[n]
                              except TypeError:
                                  d = d[idx]
                  if m:
                      rest = rest[m.end():]
                  else:
                      raise ValueError('Unable to convert '
                                       '%r at %r' % (value, rest))
          # rest should be empty
          return d
docs: Default converter for the cfg:// protocol.