code: public static TreePattern compile(final String pattern) {
  		return new TreePattern(TreeNode.parse(pattern, Decl::of));
  	}
docs: Compiles the given tree pattern string.
  
  @param pattern the tree pattern string
  @return the compiled pattern
  @throws NullPointerException if the given pattern is {@code null}
  @throws IllegalArgumentException if the given parentheses tree string
  doesn't represent a valid pattern tree