=over =item prototype FUNCTION X 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 a string starting with C, the rest is taken as a name for Perl builtin. If the builtin is not I (such as C) or its arguments cannot be expressed by a prototype (such as C) returns C because the builtin does not really behave like a Perl function. Otherwise, the string describing the equivalent prototype is returned. =back