From 6d39c90f837be0dff4eda1a18e489a9af376bc3e Mon Sep 17 00:00:00 2001
From: RnDevelover <me@ahmetyildirim.com.tr>
Date: Sun, 10 Oct 2021 01:43:22 +0200
Subject: [PATCH] Implement get_refs function for DrtLambdaExpression (#2847)

* Implement get_refs function for DrtLambdaExpression

* Update format

Co-authored-by: Ahmet Yildirim <ahmet.yildirim@iln.uio.no>
---
 nltk/sem/drt.py | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/nltk/sem/drt.py b/nltk/sem/drt.py
index 4db47fdae5..50ee8a4ade 100644
--- a/nltk/sem/drt.py
+++ b/nltk/sem/drt.py
@@ -717,6 +717,12 @@ def _pretty(self):
             + ["    " + blank + line for line in term_lines[3:]]
         )
 
+    def get_refs(self, recursive=False):
+        """:see: AbstractExpression.get_refs()"""
+        return (
+            [self.variable] + self.term.get_refs(True) if recursive else [self.variable]
+        )
+
 
 class DrtBinaryExpression(DrtExpression, BinaryExpression):
     def get_refs(self, recursive=False):