<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def decode_content(self, rpb_content, sibling):
 """ Decodes a single sibling from the protobuf representation into a RiakObject. :param rpb_content: a single RpbContent message :type rpb_content: riak.pb.riak_pb2.RpbContent :param sibling: a RiakContent sibling container :type sibling: RiakContent :rtype: RiakContent """


        if rpb_content.HasField("deleted") and rpb_content.deleted:
            sibling.exists = False
        else:
            sibling.exists = True
        if rpb_content.HasField("content_type"):
            sibling.content_type = bytes_to_str(rpb_content.content_type)
        if rpb_content.HasField("charset"):
            sibling.charset = bytes_to_str(rpb_content.charset)
        if rpb_content.HasField("content_encoding"):
            sibling.content_encoding = \
                bytes_to_str(rpb_content.content_encoding)
        if rpb_content.HasField("vtag"):
            sibling.etag = bytes_to_str(rpb_content.vtag)

        sibling.links = [self.decode_link(link)
                         for link in rpb_content.links]
        if rpb_content.HasField("last_mod"):
            sibling.last_modified = float(rpb_content.last_mod)
            if rpb_content.HasField("last_mod_usecs"):
                sibling.last_modified += rpb_content.last_mod_usecs / 1000000.0

        sibling.usermeta = dict([(bytes_to_str(usermd.key),
                                  bytes_to_str(usermd.value))
                                 for usermd in rpb_content.usermeta])
        sibling.indexes = set([(bytes_to_str(index.key),
                                decode_index_value(index.key, index.value))
                               for index in rpb_content.indexes])
        sibling.encoded_data = rpb_content.value

        return sibling