public Boolean exists(String email){
  for (  Person person : people) {
    if (email.equals(person.getEmail())) {
      return true;
    }
  }
  return false;
}

public Boolean exists ( String email ) { for ( Person person : people ) { if ( email . equals ( person . getEmail ( ) ) ) { return true ; } } return false ; }
given an email checks if the person exists in the manager .
