get_byte/[1,2]  [ISO]get_byte(-Byte)
   
get_byte(+Stream, -Byte)
   
Unifies Byte with the next byte from Stream or with -1 if there are no more bytes.
valid input binary stream,
defaults to the current input stream.
     
Stream errors (see ref-iou-sfh-est), plus:
type_errorexistence_error