Wrapper rpc call api.

Wraper rpc's client.

ErrConnect indicates error occurs connecting to the bystackd, e.g., bystackd can't parse the received arguments.

ErrLocalExe indicates error occurs before the rpc calling.

ErrLocalParse indicates error occurs locally when parsing the response.

ErrRemote indicates error occurs in bystackd.

Success indicates the rpc calling is successful.