anchor.diff:  uses std.io;
   
   unittest std.io.path.extension {
  -	var tryPathExtension = func (cref file: string, cref expect: string, cref withDot: string) {
  +	var try_path_extension = func (cref file: string, cref expect: string, cref withDot: string) {
   		var expectHas = (not withDot.empty);
   		ref expectDot = withDot;
   		ref expectNoDot = expect;
  
positive.code: 			printerr("    expect: '\(expect)'\n");
  		}
  	}
  	tryPathFolder("/foo/baz/baz.txt", expect: "/foo/baz");
  	tryPathFolder("/foo/baz/baz", expect: "/foo/baz");
  	tryPathFolder("/foo/baz//.config", expect: "/foo/baz/");
  	tryPathFolder("/foo/baz/", expect: "/foo/baz");
  	tryPathFolder("/foo/", expect: "/foo");
  	tryPathFolder("/", expect: "");
  	tryPathFolder("", expect: "");
  }
  
  unittest std.io.path.parent {
  	var tryPathParentFolder = func (cref path: string, cref expect: string) {
  		ref got = std.io.path.parent(path);
  		if got != expect then {
  			printerr("error: fail '\(path)'\n");
  
negative.code: 			printerr("    expect: has: '\(expectHas)', ext: '\(expectDot)', nodot: '\(expectNoDot)'\n");
  		}
  	}
  	try_path_extension("foo.txt", expect: "txt", withDot: ".txt");
  	try_path_extension("foo.", expect: "", withDot: ".");
  	try_path_extension(".", expect: "", withDot: ".");
  	try_path_extension("", expect: "", withDot: "");
  	try_path_extension("foo", expect: "", withDot: "");
  	try_path_extension("foo/", expect: "", withDot: "");
  	try_path_extension("foo/txt", expect: "", withDot: "");
  	try_path_extension("foo/t", expect: "", withDot: "");
  	try_path_extension("foo/baz.n", expect: "n", withDot: ".n");
  	try_path_extension("foo/baz.ny", expect: "ny", withDot: ".ny");
  	try_path_extension("foo/baz.veryVeryLong even with spaces", expect: "veryVeryLong even with spaces", withDot: ".veryVeryLong even with spaces");
  	try_path_extension("foo/.config", expect: "config", withDot: ".config");
  	try_path_extension("../../../././././foo.bmp", expect: "bmp", withDot: ".bmp");
  }
  
  unittest std.io.path.filename {
  	var try_path_filename = func (cref path: string, cref expect: string) {
  		ref got = std.io.path.filename(path);
  		if got != expect then {
  			printerr("error: fail '\(path)'\n");
  