ns for lexer semantic actions</h2><p>The following functions can be called from the semantic actions
   of lexer definitions (the ML code enclosed in braces that
   computes the value returned by lexing functions). They give
   access to the character string matched by the regular expression
   associated with the semantic action. These functions must be
   applied to the argument <code class="code">lexbuf</code>, which, in the code generated by
   <code class="code">ocamllex</code>, is bound to the lexer b