code: func ParseFile(fileSet *file.FileSet, filename string, src interface{}, mode Mode) (*ast.Program, error) {
  	return ParseFileWithSourceMap(fileSet, filename, src, nil, mode)
  }
docs: // ParseFile parses the source code of a single JavaScript/ECMAScript source file and returns
  // the corresponding ast.Program node.
  //
  // If fileSet == nil, ParseFile parses source without a FileSet.
  // If fileSet != nil, ParseFile first adds filename and src to fileSet.
  //
  // The filename argument is optional and is used for labelling errors, etc.
  //
  // src may be a string, a byte slice, a bytes.Buffer, or an io.Reader, but it MUST always be in UTF-8.
  //
  //      // Parse some JavaScript, yielding a *ast.Program and/or an ErrorList
  //      program, err := parser.ParseFile(nil, "", `if (abc > 1) {}`, 0)
  //