Dpkg::Deps::Union - list of unrelated dependencies
This object represents a list of relationships. It inherits from
    Dpkg::Deps::Multiple.
  - $dep->output([$fh])
- The output method uses ", " to join the list of
    relationships.
- $dep->implies($other_dep)
- $dep->get_evaluation($other_dep)
- These methods are not meaningful for this object and always return
    undef.
- $dep->simplify_deps($facts)
- The simplification is done to generate an union of all the relationships.
      It uses $simple_dep->merge_union($other_dep) to
      get its job done.
Mark the module as public.