pub enum TmqMessage  {
    Single(zmq::Message),
    MultiPart(Vec<zmq::Message>)
}


// I can have one or the other, but not both

impl From<zmq::Message> for TmqMessage {
    fn from(msg: zmq::Message) -> Self {
        TmqMessage::Single(msg)
    }
}

impl<I: Iterator<Item=zmq::Message>> From<I> for TmqMessage {
    fn from(msgs: I) -> Self {
        TmqMessage::MultiPart(msgs.collect())
    }
}

/* Error from compiler:

error[E0119]: conflicting implementations of trait `std::convert::From<zmq::Message>` for type `poll::TmqMessage`:
  --> src/poll.rs:41:1
   |
35 | impl From<zmq::Message> for TmqMessage {
   | -------------------------------------- first implementation here
...
41 | impl<I: Iterator<Item=zmq::Message>> From<I> for TmqMessage {
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation for `poll::TmqMessage`
   |
   = note: upstream crates may add new impl of trait `std::iter::Iterator` for type `zmq::Message` in future versions

error: aborting due to previous error

For more information about this error, try `rustc --explain E0119`.
error: Could not compile `tmq`.


*/