code: public boolean containsMember(Address mbr) {
          if(mbr == null || members == null)
              return false;
          for(Address member: members)
              if(Objects.equals(member, mbr))
                  return true;
          return false;
      }
docs: Returns true if this view contains a certain member
  @param mbr - the address of the member,
  @return true if this view contains the member, false if it doesn't