From 40ee32e0659714a7711b65c168c75a82c00bef8b Mon Sep 17 00:00:00 2001
From: Viicos <65306057+Viicos@users.noreply.github.com>
Date: Tue, 23 May 2023 01:30:46 +0200
Subject: [PATCH] refactor: use `None` for `dict` default values (#831)

---
 diagrams/__init__.py | 18 +++++++++++++-----
 1 file changed, 13 insertions(+), 5 deletions(-)

diff --git a/diagrams/__init__.py b/diagrams/__init__.py
index 6e282d9..6fe2a80 100644
--- a/diagrams/__init__.py
+++ b/diagrams/__init__.py
@@ -2,7 +2,7 @@ import contextvars
 import os
 import uuid
 from pathlib import Path
-from typing import List, Union, Dict
+from typing import Dict, List, Optional, Union
 
 from graphviz import Digraph
 
@@ -86,9 +86,9 @@ class Diagram:
         autolabel: bool = False,
         show: bool = True,
         strict: bool = False,
-        graph_attr: dict = {},
-        node_attr: dict = {},
-        edge_attr: dict = {},
+        graph_attr: Optional[dict] = None,
+        node_attr: Optional[dict] = None,
+        edge_attr: Optional[dict] = None,
     ):
         """Diagram represents a global diagrams context.
 
@@ -105,6 +105,12 @@ class Diagram:
         :param edge_attr: Provide edge_attr dot config attributes.
         :param strict: Rendering should merge multi-edges.
         """
+        if graph_attr is None:
+            graph_attr = {}
+        if node_attr is None:
+            node_attr = {}
+        if edge_attr is None:
+            edge_attr = {}
         self.name = name
         if not name and not filename:
             filename = "diagrams_image"
@@ -215,7 +221,7 @@ class Cluster:
         self,
         label: str = "cluster",
         direction: str = "LR",
-        graph_attr: dict = {},
+        graph_attr: Optional[dict] = None,
     ):
         """Cluster represents a cluster context.
 
@@ -223,6 +229,8 @@ class Cluster:
         :param direction: Data flow direction. Default is 'left to right'.
         :param graph_attr: Provide graph_attr dot config attributes.
         """
+        if graph_attr is None:
+            graph_attr = {}
         self.label = label
         self.name = "cluster_" + self.label