@Serial
	private Object writeReplace() {
		return new SerialProxy(SerialProxy.TREE_REWRITE_RULE, this);
	}
Compiles the string representation of a rewrite rule:
<pre> {@code
    add($x,0) -> $x
    mul($x,1) -> $x
} </pre>

@param rule the rewrite rule
@return a new rewrite rule, compiled from the given rule string
@throws IllegalArgumentException if the rewrite rule is invalid
@throws NullPointerException if on of the arguments is {@code null}
jenetics.ext/src/main/java/io/jenetics/ext/rewriting/TreeRewriteRule.java