diff --git a/2020/Day07.cs b/2020/Day07.cs
index d7bffa8..156a9ff 100644
--- a/2020/Day07.cs
+++ b/2020/Day07.cs
@@ -46,11 +46,12 @@ namespace AdventOfCode {
       return contains;
     }
 
-    static int ComputePart1(List<Contains> contains) {
-      int setSize = 0;
+    static int WhatCanContain(List<Contains> contains, string target) {
       var result = new HashSet<string>();
-      result.Add("shiny gold");
+      int setSize = 0;
+      result.Add(target);
 
+      // transitive closure: keep adding things, until a round of doing so doesn't add anything new
       while (true) {
         foreach (Contains c in contains) {
           if (result.Contains(c.Inner)) {
@@ -58,7 +59,7 @@ namespace AdventOfCode {
           }
         }
         if (result.Count() == setSize) {  // nothing new to add, we're done
-          return result.Count() - 1;  // shiny gold doesn't contain itself
+          return result.Count() - 1;  // our target doesn't actually contain itself
         }
         setSize = result.Count();
       }
@@ -76,7 +77,7 @@ namespace AdventOfCode {
 
     static int Part1() {
       List<Contains> contains = ParseRules(File.ReadAllLines(Util.RootDir + "day07.txt"));
-      return ComputePart1(contains);
+      return WhatCanContain(contains, "shiny gold");
     }
 
     static int Part2() {
@@ -97,7 +98,7 @@ vibrant plum bags contain 5 faded blue bags, 6 dotted black bags.
 faded blue bags contain no other bags.
 dotted black bags contain no other bags.".Split('\n');
 
-      Assert.Equal(4, ComputePart1(ParseRules(example)));
+      Assert.Equal(4, WhatCanContain(ParseRules(example), "shiny gold"));
       Assert.Equal(213, Part1());
 
       string[] example2 =