Update src/Std/Data/DTreeMap/Internal/Lemmas.lean

Co-authored-by: Paul Reichert <[email protected]>

Author: wkrozowski

src/Std/Data/DTreeMap/Internal/Lemmas.lean

@@ -3545,7 +3545,7 @@ theorem getD_union_of_contains_eq_false_right [TransOrd α] [LawfulEqOrd α] (h
     exact contains_eq_false
 
 theorem getD_union!_of_contains_eq_false_right [TransOrd α] [LawfulEqOrd α] (h₁ : m₁.WF) (h₂ : m₂.WF)
-    {k : α} {fallback : β k} (contains_eq_false : m₂.contains k = false)  :
+    {k : α} {fallback : β k} (contains_eq_false : m₂.contains k = false) :
     (m₁.union! m₂).getD k fallback = m₁.getD k fallback := by
   rw [← union_eq_union!]
   apply getD_union_of_contains_eq_false_right h₁ h₂