public void testToString() {
    assertToStringWorks(CharMatcher.anyOf(""), "CharMatcher.none()");
    assertToStringWorks(CharMatcher.anyOf("1"), "CharMatcher.is('\\u0031')");
    assertToStringWorks(CharMatcher.isNot('1'), "CharMatcher.isNot('\\u0031')");
    assertToStringWorks(CharMatcher.anyOf("12"), "CharMatcher.anyOf(\"\\u0031\\u0032\")");
    assertToStringWorks(CharMatcher.anyOf("321"), "CharMatcher.anyOf(\"\\u0031\\u0032\\u0033\")");

// numbers and booleans.

// Supported comparison operators
const (
	opLt    = "<"
	opLte   = "<="
	opGt    = ">"
	opGte   = ">="
	opEq    = "="
	opIneq  = "!="
	opIs    = "IS"
	opIsNot = "ISNOT"
)

// InferBytesType will attempt to infer the data type of bytes.
// Will fail if value type is not bytes or it would result in invalid utf8.
// ORDER: int, float, bool, JSON (object or array), timestamp, string

  /** Matcher for type, subtype and attributes. */
  private static final CharMatcher TOKEN_MATCHER =
      ascii()
          .and(javaIsoControl().negate())
          .and(CharMatcher.isNot(' '))
          .and(CharMatcher.noneOf("()<>@,;:\\\"/[]?="));

  private static final CharMatcher QUOTED_TEXT_MATCHER = ascii().and(CharMatcher.noneOf("\"\\\r"));

  /*