public Builder<T> separator(final T separator) {
			return separator(token -> Objects.equals(token, separator));
		}
Set the <em>prototype</em> for the {@code separator} token. A given
token is treated as  {@code separator} if {@code Objects.equals(token, separator)}
returns {@code true}.

@param separator the {@code separator} prototype
@return {@code this} builder, for method chaining
jenetics.ext/src/main/java/io/jenetics/ext/internal/util/FormulaParser.java