code: def prepend(self, key, value, cas=0, format=None,
                  persist_to=0, replicate_to=0):
          
          return _Base.prepend(self, key, value, cas=cas, format=format,
                               persist_to=persist_to, replicate_to=replicate_to)
docs: Prepend a string to an existing value in Couchbase.
  
          .. seealso:: :meth:`append`, :meth:`prepend_multi`