diff --git a/rolltable/tables.py b/rolltable/tables.py
index df5f191..3ffa5c4 100644
--- a/rolltable/tables.py
+++ b/rolltable/tables.py
@@ -87,12 +87,15 @@ class DataSource:
         ]
 
     def as_dict(self) -> dict:
+        """
+        Return the contents of the data source as a dict.
+        """
         data = dict()
         for name in self.data.keys():
             entries = self.get_entries(name, rand=False)
             headers = self.headers
             for i in range(0, len(self.headers) - len(entries[0])):
-                headers.append(f"{i:3f}", i)
+                headers.append(f"{i:3f}")
             items = {(k, v) for k, v in zip(self.headers, self.get_entries(name))}
             print(items)
             data[name] = dict(items)