sub method_a {
   ...
   open(...) or die "First ...";
   ...
   $self->_method_b();
}

sub _method_b {
   ...
   open(...) or die "Second ...";
   $self->_method_c();
}

sub _method_c {
   ...
   open(...) or die "Third ...";
}


##</code><code>##

if ( $caller eq '_method_c') {
    return 0;
}
return 1;
}