Please see https://github.com/Real-Serious-Games/C-Sharp-Promise

Installation instructions

• Open your project manifest file (MyProject/Packages/manifest.json).
• Add "com.rsg.promises": "https://github.com/debox-dev/RSG_Promises.git" to the dependencies list.
• Open or focus on Unity Editor to resolve packages.