Undocumented predicates

The following predicates are exported, but not or incorrectly documented.

 rs_init(Arg1)

 rs_call(Arg1, Arg2)

 rs_eval(Arg1, Arg2, Arg3)

 rs_submit(Arg1, Arg2, Arg3)

 rs_close(Arg1)

 rx_call(Arg1)

 rx_eval(Arg1, Arg2)

 rx_submit(Arg1, Arg2)

 r_init

 r_call(Arg1)

 r_eval(Arg1, Arg2)

 <-(Arg1)

 <-(Arg1, Arg2)