public ContractReturnValue intersect(ContractReturnValue other) {
    if (this.equals(other) || other == ANY_VALUE) return this;
    if (this == ANY_VALUE) return other;
    if (this.isNotNull() && other.isNotNull()) return NOT_NULL_VALUE;
    return FAIL_VALUE;
  }
public ContractReturnValue intersect(ContractReturnValue other)