From 26efbd7c3d5975bf04a20e0553ea948ed26409de Mon Sep 17 00:00:00 2001
From: Shyam D <shyamd@lbl.gov>
Date: Tue, 25 May 2021 09:23:50 -0700
Subject: [PATCH] make MPID hashable

---
 emmet-core/emmet/core/mpid.py | 3 +++
 tests/emmet-core/test_mpid.py | 5 +++++
 2 files changed, 8 insertions(+)

diff --git a/emmet-core/emmet/core/mpid.py b/emmet-core/emmet/core/mpid.py
index bdf0aa988b..fd51ed8002 100644
--- a/emmet-core/emmet/core/mpid.py
+++ b/emmet-core/emmet/core/mpid.py
@@ -54,6 +54,9 @@ def __lt__(self, other: Union["MPID", int, str]):
 
         return self.parts < other_parts
 
+    def __hash__(self):
+        return hash(self.parts)
+
     @classmethod
     def __get_validators__(cls):
         yield cls.validate
diff --git a/tests/emmet-core/test_mpid.py b/tests/emmet-core/test_mpid.py
index a7b6c7ddc5..b43ccd1402 100644
--- a/tests/emmet-core/test_mpid.py
+++ b/tests/emmet-core/test_mpid.py
@@ -11,6 +11,11 @@ def test_mpid():
 
     assert min([MPID("mp-44545"), MPID("mp-33"), MPID("mp-2134234")]) == MPID("mp-33")
 
+    assert (
+        len(set([MPID("mp-33"), MPID("mp-44545"), MPID("mp-33"), MPID("mp-2134234")]))
+        == 3
+    )
+
 
 def test_to_str():
     assert str(MPID("mp-149")) == "mp-149"