code: public static Keyword keyword(Object o) {
          if (o instanceof Keyword)
              return (Keyword) o;
          else if (o instanceof String) {
              String s = (String) o;
              if (s.charAt(0) == ':')
                  return new KeywordImpl(s.substring(1));
              else
                  return new KeywordImpl(s);
          }
          else throw new IllegalArgumentException("Cannot make keyword from " + o.getClass().getSimpleName());
      }
docs: Converts a string or keyword to a keyword
  @param o A string or a keyword
  @return a keyword