code: func (cp *ComparablePrincipal) ToOURole() *ComparablePrincipal {
  	ouRole := &msp.OrganizationUnit{}
  	err := proto.Unmarshal(cp.principal.Principal, ouRole)
  	if err != nil {
  		logger.Warning("Failed unmarshaling principal:", err)
  		return nil
  	}
  	cp.mspID = ouRole.MspIdentifier
  	cp.ou = ouRole
  	return cp
  }
docs: // ToOURole converts this ComparablePrincipal to OU principal, and returns nil on failure