function isDefinedHashType(hashType) {
  const hashTypeMod = hashType & ~0x80;
  return hashTypeMod > 0x00 && hashTypeMod < 0x04;
}
Checks if the provided hash type is defined.

A hash type is considered defined if its modified value (after masking with ~0x80)
is greater than 0x00 and less than 0x04.

@param hashType - The hash type to check.
@returns True if the hash type is defined, false otherwise.