glimmer.rb in glimmer-1.0.8

- old
+ new

@@ -20,9 +20,10 @@
 # WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 
 require 'logger'
 require 'set'
 require 'array_include_methods'
+require 'concurrent-ruby'
 
 $LOAD_PATH.unshift(File.expand_path('..', __FILE__))
 
 require 'glimmer/config'
 