Add PyItem container

Also reduce queue item trait bound from Ord to just PartialOrd

src/backing/containers/py_item.rs

@@ -0,0 +1,46 @@
+use std::cmp::Ordering;
+
+use pyo3::prelude::*;
+
+/// Container that provides PartialOrd based on the Python object it holds
+#[derive(Debug, Clone)]
+pub struct PyItem(Py<PyAny>);
+
+impl PyItem {
+    /// Creates a new instance
+    fn new(item: Py<PyAny>) -> Self {
+        PyItem(item)
+    }
+
+    /// Retrieves the internal data
+    fn item(self) -> Py<PyAny> {
+        self.0
+    }
+}
+
+impl PartialOrd for PyItem {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        Python::with_gil(|py| {
+            // Bind objects for convenience
+            let ours = self.0.bind(py);
+            let theirs = other.0.bind(py);
+
+            // Compare based on Python comparison implementations
+            match ours.lt(theirs) {
+                Ok(true) => Some(Ordering::Less),
+                Ok(false) => match ours.gt(theirs) {
+                    Ok(true) => Some(Ordering::Greater),
+                    Ok(false) => Some(Ordering::Equal), // If the python class is implemented strangely then this may be wrong
+                    Err(_) => None,
+                },
+                Err(_) => None,
+            }
+        })
+    }
+}
+
+impl PartialEq for PyItem {
+    fn eq(&self, other: &Self) -> bool {
+        Python::with_gil(|py| self.0.bind(py).eq(other.0.bind(py)).unwrap_or(false))
+    }
+}