1 files changed, 30 insertions, 0 deletions
diff --git a/itertoolset.py b/itertoolset.py
new file mode 100644
index 0000000..ae4be8a
--- /dev/null
+++ b/itertoolset.py
@@ -0,0 +1,30 @@
+from itertools import *
+
+def roundrobin(*iterables):
+    """roundrobin('ABC', 'D', 'EF') --> A D E B F C"""
+    pending = len(iterables)
+    nexts = cycle(iter(it).next for it in iterables)
+    while pending:
+        try:
+            for next in nexts:
+                yield next()
+        except StopIteration:
+            pending -= 1
+            nexts = cycle(islice(nexts, pending))
+
+def unique_everseen(iterable, key=None):
+    "List unique elements, preserving order. Remember all elements ever seen."
+    # unique_everseen('AAAABBBCCDAABBB') --> A B C D
+    # unique_everseen('ABBCcAD', str.lower) --> A B C D
+    seen = set()
+    seen_add = seen.add
+    if key is None:
+        for element in ifilterfalse(seen.__contains__, iterable):
+            seen_add(element)
+            yield element
+    else:
+        for element in iterable:
+            k = key(element)
+            if k not in seen:
+                seen_add(k)
+                yield element