From 40ac0edc686b0ea52b8574ba112820d925c6d87b Mon Sep 17 00:00:00 2001
From: Ryan Miller <ryan@devopsmachine.com>
Date: Mon, 13 Apr 2020 23:14:40 -0400
Subject: [PATCH] Verify Edge attributes exist before setting

---
 diagrams/__init__.py | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/diagrams/__init__.py b/diagrams/__init__.py
index 9626ea6..e119a60 100644
--- a/diagrams/__init__.py
+++ b/diagrams/__init__.py
@@ -436,10 +436,13 @@ class Edge:
         for k, v in self._default_edge_attrs.items():
             self._attrs[k] = v
 
-        # Graphviz complaining about using label for edges, so replace it with xlabel.
-        self._attrs["xlabel"] = label
-        self._attrs["color"] = color
-        self._attrs["style"] = style
+        if label:
+            # Graphviz complaining about using label for edges, so replace it with xlabel.
+            self._attrs["xlabel"] = label
+        if color:
+            self._attrs["color"] = color
+        if style:
+            self._attrs["style"] = style
         self._attrs.update(attrs)
 
     def __sub__(self, other: Union["Node", "Edge", List["Node"]]):