code: func (r *Route) Queries(pairs ...string) *Route {
  	length := len(pairs)
  	if length%2 != 0 {
  		r.err = fmt.Errorf(
  			"mux: number of parameters must be multiple of 2, got %v", pairs)
  		return nil
  	}
  	for i := 0; i < length; i += 2 {
  		if r.err = r.addRegexpMatcher(pairs[i]+"="+pairs[i+1], regexpTypeQuery); r.err != nil {
  			return r
  		}
  	}
  
  	return r
  }
docs: // Query ----------------------------------------------------------------------
  // Queries adds a matcher for URL query values.
  // It accepts a sequence of key/value pairs. Values may define variables.
  // For example:
  //
  //     r := mux.NewRouter()
  //     r.Queries("foo", "bar", "id", "{id:[0-9]+}")
  //
  // The above route will only match if the URL contains the defined queries
  // values, e.g.: ?foo=bar&id=42.
  //
  // If the value is an empty string, it will match any value if the key is set.
  //
  // Variables can define an optional regexp pattern to be matched:
  //
  // - {name} matches anything until the next slash.
  //
  // - {name:pattern} matches the given regexp pattern.