Query your object to see if it provides the necessary API. If so, use it. If not, try the fallback. If that doesn't exist, bitch at the user.

sub fulfills_interface_foo {
    my $self = shift;
    return $self->can( ... )
        and $self->can( ... )
        and $self->can( ... )
        and $self->can( ... );
}
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