module ActiveFedora::SpawnMethods

def merge!(other) # :nodoc:
  if !other.is_a?(Relation) && other.respond_to?(:to_proc)
    instance_exec(&other)
  else
    klass = other.is_a?(Hash) ? Relation::HashMerger : Relation::Merger
    klass.new(self, other).merge
  end
end