ch11-24: clean up by @eumiro & sync with Atlas

17-it-generator/aritprog_v3.py

@@ -0,0 +1,11 @@
+# tag::ARITPROG_ITERTOOLS[]
+import itertools
+
+
+def aritprog_gen(begin, step, end=None):
+    first = type(begin + step)(begin)
+    ap_gen = itertools.count(first, step)
+    if end is not None:
+        ap_gen = itertools.takewhile(lambda n: n < end, ap_gen)
+    return ap_gen
+# end::ARITPROG_ITERTOOLS[]