There are two ways of skipping over characters in the current input stream: skip to a given character, or skip to the end of a line.
skip_byte(N) skips over bytes through the first
occurrence of N from the current input stream, which must be binary.
skip_code(N) skips over character codes through the first
occurrence of N from the current input stream, which must be text.
skip_char(A) skips over character atoms through the first
occurrence of A from the current input stream, which must be text.
skip_line skips to the end of line of the current input stream.
Use of this predicate helps portability of code
since it avoids dependence on any particular character code(s) being
returned at the end of a line.