SetInput
Implements ISO's set_input/1: makes the stream identified by the argument (an alias or $stream(...) term) the current input stream, i.e. the one implicitly used by unary predicates like Read1 and GetChar1 (see IOPrimitiveUtils.currentInputChannel).
Throws
if the argument is unbound.
if it does not identify an open channel.
(stream_type) if it identifies an output channel instead.