function compareBase64Mixed (actualValue, expectedValue) {
  if (actualValue.length !== expectedValue.length) {
    return false
  }
  for (let i = 0; i < actualValue.length; ++i) {
    if (actualValue[i] !== expectedValue[i]) {
      if (
        (actualValue[i] === '+' && expectedValue[i] === '-') ||
        (actualValue[i] === '/' && expectedValue[i] === '_')
      ) {
        continue
      }
      return false
    }
  }

  return true
}
Compares two base64 strings, allowing for base64url
in the second string.

@param {string} actualValue always base64
@param {string} expectedValue base64 or base64url
@returns {boolean}