code: function(node, file) {
      node.content = file.ast.content;
      node.uri = node.uri || file.file;
      node.file = file.file;
    }
docs: Maps an AST node to a resolved file.
  Applies standard meta data to imported nodes:
  - contents: applies the imported file contents as the node tree.
  - uri: the original (probably relative) reference used to import the file.
  - file: the resolved (definitely absolute) file path that the import loaded.