/// Creates a namespaced selector using the configured `namespace-tag` string.
/// For example:
/// ```
///   @include A(with-namespace, "hello", "world") {
///     background-color: red;
///   }
/// ```
/// would produce a selector like: `.hello/world` (under the default
/// configuration).
@mixin anthology-with-namespace($namespace, $identifier)
{
  $namepace-tag: $_anthology-config-namespace-tag;
  $selector: '.#{$namespace}#{$namepace-tag}#{$identifier}';

  #{$selector} {
    @content;
  }
}