/bin/sh: yo: command not found
Somehow I got this error on my macOS
```shell
$ create-graphql generate --mutation Awesome
✗ GraphQL CLI requires Yeoman to be installed.
✓ Yeoman installed!
/bin/sh: yo: command not found
(node:37016) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 1): Error: Exited with status 127
(node:37016) DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.
```
FYI
```
$ node --version
v7.4.0
```

Any hint?