src/language-js/print/module.js/printImportAssertions
function printImportAssertions(path, options, print) {
  const node = path.getNode();
  if (isNonEmptyArray(node.assertions)) {
    return [
      " assert {",
      options.bracketSpacing ? " " : "",
      join(", ", path.map(print, "assertions")),
      options.bracketSpacing ? " " : "",
      "}",
    ];
  }
  return "";
}