code: @DontLabel
      public Rule firstOf(final Object rule, final Object rule2,
          final Object... moreRules)
      {
          Objects.requireNonNull(moreRules);
          final Object[] rules = ImmutableList.builder().add(rule).add(rule2)
              .add(moreRules).build().toArray();
          return firstOf(rules);
      }
docs: Match the first rule of a series of rules
  
  <p>When one rule matches, all others are ignored.</p>
  
  <p>Note: if you are considering matching one string among many, consider
  using {@link #trie(Collection)}/{@link #trie(String, String, String...)}
  instead.</p>
  
  @param rule the first subrule
  @param rule2 the second subrule
  @param moreRules the other subrules
  @return a rule