# File lib/openstack.rb, line 97
  def self.get_query_params(params, keys, url="")
    set_keys = params.inject([]){|res, (k,v)| res << k if keys.include?(k) and not v.nil?; res }
    return url if set_keys.empty?
    url = "#{url}?#{set_keys[0]}=#{params[set_keys[0]]}"
    set_keys.slice!(0)
    set_keys.each do |k|
      url = "#{url}&#{k}=#{params[set_keys[0]]}"
    end
    url
  end