class Middleman::Sitemap::Queryable::Query

def where(constraints_hash)
  selector_hash = constraints_hash.reject { |key, value| !key.is_a? Selector }
  symbol_hash = constraints_hash.reject { |key, value| key.is_a? Selector }
  symbol_hash.each do |attribute, value|
    selector = Selector.new(:attribute => attribute, :operator => 'equal')
    selector_hash.update({ selector => value })
  end
  @where.merge! selector_hash
  self
end