if s == "CFType" {
		return true
	}
	if c.getTypeIDs[s] {
		return true
	}
	if i := strings.Index(s, "Mutable"); i >= 0 && c.getTypeIDs[s[:i]+s[i+7:]] {
		// Mutable and immutable variants share a type ID.
		return true
	}
	return false
}

// Comment from Darwin's CFInternal.h
/*
// Tagged pointer support
// Low-bit set means tagged object, next 3 bits (currently)