Results of today's code review session.

inventory.cpp

@@ -29,4 +29,14 @@ namespace components {
     dbc::check(at < items.size(), fmt::format("inventory index {} too big", at));
     items.erase(items.begin() + at);
   }
+
+  int Inventory::item_index(std::string id) {
+    for(size_t i = 0; i < items.size(); i++) {
+      if(items[i].data["id"] == id) {
+        return i;
+      }
+    }
+
+    return -1;
+  }
 }