### Question:
Snippets { public static Snippet id(final Object object) { return id(object, (Object[])null); } private  Snippets(); static String source(final String template, final Object... args); static String source(final Object... snippets); static Snippet list(final Stream<?> items, final Object separator); static Snippet id(final Object object); static Snippet id(final Object object, final Object... aliases);  }### Answer:
@Test void testId() { final Object x=new Object(); final Object y=new Object(); final Object z=new Object(); assertThat(source(id(x))) .as("formatted") .matches("\\d+"); assertThat(source(id(x), "=", id(x))) .as("idempotent") .matches("(\\d+)=\\1"); assertThat(source(id(x), "!=", id(y))) .as("unique") .doesNotMatch("(\\d+)!=\\1"); assertThat(source(id(x, y, z), "=", id(y), "=", id(z))) .as("aliased") .matches("(\\d+)=\\1=\\1"); Assertions.assertThatThrownBy(() -> source(id(x, z), id(y, z))) .as("clashes trapped") .isInstanceOf(IllegalStateException.class); }