first_char(in, out, in) failed
first_char(in, out, out) failed
first_char(in, in, in) failed
first_char(in, in, out) failed
first_char(in, in, in) failed
first_char(in, in, out) failed
first_char(in, in, in) failed
first_char(in, in, out) failed
first_char(out, in, in) threw exception: software_error("predicate `string.first_char_str_out\'/3: Unexpected: surrogate code point")
first_char(out, in, in) threw exception: software_error("predicate `string.first_char_str_out\'/3: Unexpected: surrogate code point")