yarn : File C:\Users\james\AppData\Roaming\npm\yarn.ps1 cannot be loaded because running scripts is disabled on this system. code example
Example: AppData\Roaming\npm\react-native.ps1 cannot be loaded because running scripts is disabled on this system. For more information, see about_Execution_Policies at https:/go.microsoft.com/fwlink/?LinkID=135170.
Set-ExecutionPolicy -Scope CurrentUser -ExecutionPolicy Unrestricted