code: def make_key(self, value):
          
          if value:
              parts = [self.key_filter.sub('', x)
                       for x in self.key_split.split(value.lower())]
              key = parts[0] + ''.join(map(str.capitalize, parts[1:]))
          else:
              key = ''
          if key in self.seen_keys:
              i = 1
              while '%s%d' % (key, i) in self.seen_keys:
                  i += 1
              key = '%s%d' % (key, i)
          self.seen_keys.add(key)
          return key
docs: Make camelCase variant of value.