code: func (cp *ComparablePrincipal) IsFound(set ...*ComparablePrincipal) bool {
  	for _, cp2 := range set {
  		if cp.IsA(cp2) {
  			return true
  		}
  	}
  	return false
  }
docs: // IsFound returns whether the ComparablePrincipal is found among the given set of ComparablePrincipals
  // For the ComparablePrincipal x to be found, there needs to be some ComparablePrincipal y in the set
  // such that x.IsA(y) will be true.