DB<128>   $CORE::{substr}
 => *CORE::substr

  DB<129>   $CORE::{print}
 => undef

##</code><code>##

prototype FUNCTION
               Returns the prototype of a function as a string (or "undef" 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 "CORE::", the rest is
               taken as a name for Perl builtin.  If the builtin is not
               overridable (such as "qw//") or if its arguments cannot be
               adequately expressed by a prototype (such as "system"),
               prototype() returns "undef", because the builtin does not
               really behave like a Perl function.  Otherwise, the string
               describing the equivalent prototype is returned.

##</code><code>##

  DB<131> prototype 'CORE::print'
 => undef

  DB<132> prototype 'CORE::substr'
 => "\$\$;\$\$"

##</code><code>##

  DB<133> CORE::print("bla")
bla