title: How exactly an empty "azurerm_subscription" data balock gets its Data Source Arguments?
body: <p>In the following example:</p>
  <p><a href="https://github.com/terraform-providers/terraform-provider-azurerm/blob/master/examples/app-service/function-azure-RBAC-role-assignment/main.tf" rel="nofollow noreferrer">https://github.com/terraform-providers/terraform-provider-azurerm/blob/master/examples/app-service/function-azure-RBAC-role-assignment/main.tf</a></p>
  <p>We have this code snippet:</p>
  <p><a href="https://i.stack.imgur.com/QjmGU.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/QjmGU.png" alt="enter image description here" /></a></p>
  <p>In line 57, where the value of <code>data.azurerm_subscription.primary.id</code> is coming from? I am asking since The data block in the line 53 is empty.</p>