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

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

// 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"));

  /*