code: func (n *NodeApplyableModuleVariable) ReferenceOutside() (selfPath, referencePath addrs.ModuleInstance) {
  
  	// Module input variables have their value expressions defined in the
  	// context of their calling (parent) module, and so references from
  	// a node of this type should be resolved in the parent module instance.
  	referencePath = n.Addr.Module.Parent()
  
  	// Input variables are _referenced_ from their own module, though.
  	selfPath = n.Addr.Module
  
  	return // uses named return values
  }
docs: // GraphNodeReferenceOutside implementation