code: func (id *PolicyEvaluator) Evaluate(policyBytes []byte, signatureSet []*common.SignedData) error {
  	pp := cauthdsl.NewPolicyProvider(id.IdentityDeserializer)
  	policy, _, err := pp.NewPolicy(policyBytes)
  	if err != nil {
  		return err
  	}
  	return policy.Evaluate(signatureSet)
  }
docs: // Evaluate takes a set of SignedData and evaluates whether this set of signatures satisfies the policy