next steps for closure iterators

tests/controlflow/tnestif.nim

@@ -0,0 +1,24 @@
+discard """
+  file: "tnestif.nim"
+  output: "i == 2"
+"""
+# test nested ifs
+
+var
+    x, y: int
+x = 2
+if x == 0:
+    write(stdout, "i == 0")
+    if y == 0:
+        write(stdout, x)
+    else:
+        write(stdout, y)
+elif x == 1:
+    write(stdout, "i == 1")
+elif x == 2:
+    write(stdout, "i == 2")
+else:
+    write(stdout, "looks like Python")
+#OUT i == 2
+
+