sub sub2 {
  my ($self) = @_;
  $self->_sub1;
}

##</code><code>##

# Use goto because that automatically passes on @_ to the
# next function.
sub sub2 {
    goto \&_sub1;
}

##</code><code>##

# Just make one sub into an alias for the other...
*sub2 = \&_sub1;