=over =item prototype FUNCTION X =item prototype Returns the prototype of a function as a string (or C if the function has no prototype). FUNCTION is a reference to, or the name of, the function whose prototype you want to retrieve. If FUNCTION is omitted, $_ is used. If FUNCTION is a string starting with C, the rest is taken as a name for a Perl builtin. If the builtin's arguments cannot be adequately expressed by a prototype (such as C), prototype() returns C, because the builtin does not really behave like a Perl function. Otherwise, the string describing the equivalent prototype is returned. =back