class JWT::Decode

def verify_algo
  raise(JWT::IncorrectAlgorithm, 'An algorithm must be specified') if allowed_algorithms.empty?
  raise(JWT::IncorrectAlgorithm, 'Token is missing alg header') unless alg_in_header
  raise(JWT::IncorrectAlgorithm, 'Expected a different algorithm') if allowed_and_valid_algorithms.empty?
end