public Builder<T> rparen(final Predicate<? super T> rparen) {
			_rparen = requireNonNull(rparen);
			return this;
		}
Set the predicate which defines {@code rparen} tokens. If the given
predicate returns {@code true} for a token, it is treated as
<em>rparen</em>.

@param rparen the {@code rparen} token
@return {@code this} builder, for method chaining
@throws NullPointerException if the {@code rparen} is {@code null}
jenetics.ext/src/main/java/io/jenetics/ext/internal/util/FormulaParser.java