@SuppressWarnings({"regex","purity.not.deterministic.call"}) public static boolean isRegex(final char c){
  return isRegex(Character.toString(c));
}

@ SuppressWarnings ( { "regex" , "purity.not.deterministic.call" } ) public static boolean isRegex ( final char c ) { return isRegex ( Character . toString ( c ) ) ; }
returns true if the argument is a syntactically valid regular expression .
