More progress.

src/lib.rs

@@ -247,6 +247,14 @@ impl<'a, T, B> ops::BitOr<&'a Self> for BitSet<T, B> where T: Block, B: Block {
         self
     }
 }
+
+pub struct Iter<'a, T: 'a, B: 'a> {
+    iter: std::collections::hash_map::Iter<'a, T, B>,
+    block: T,
+    bits: B,
+    bit: B,
+}
+
 /*
 pub struct Iter<'a> {
     iter: std::collections::hash_map::Iter<'a, u64, u64>,