message: Add isSelectablePath()
diff: @@ -10,6 +10,7 @@ export {
  SelectableIdentifier,
  SelectableVariableDeclarator,
  Selectable,
  + isSelectablePath,
  isSelectableNode,
  isSelectableVariableDeclarator,
  isSelectableIdentifier,
  @@ -26,7 +27,7 @@ interface ASTPosition {
  column: number;
  }
  -type SelectablePath = NodePath<SelectableNode>;
  +type SelectablePath<T = t.Node> = NodePath<Selectable<T>>;
  type SelectableNode = Selectable<t.Node>;
  type SelectableIdentifier = Selectable<t.Identifier>;
  type SelectableVariableDeclarator = Selectable<t.VariableDeclarator>;
  @@ -38,6 +39,12 @@ interface SelectableObjectProperty extends t.ObjectProperty {
  value: Selectable<t.ObjectProperty["value"]>;
  }
  +function isSelectablePath<T extends t.Node>(
  + path: NodePath<T>
  +): path is SelectablePath<T> {
  + return !!path.node.loc;
  +}
  +
  function isSelectableNode(node: t.Node | null): node is SelectableNode {
  return !!node && !!node.loc;
  }
  