From a17e5e4f8d9d9b8e1932bda10a1ab5cf59290deb Mon Sep 17 00:00:00 2001
From: Bo Bayles <bbayles@gmail.com>
Date: Mon, 14 May 2018 21:20:08 -0500
Subject: [PATCH] Add prepend recipe

---
 docs/api.rst                         |  1 +
 more_itertools/recipes.py            | 15 +++++++++++++++
 more_itertools/tests/test_recipes.py | 16 ++++++++++++++++
 3 files changed, 32 insertions(+)

diff --git a/docs/api.rst b/docs/api.rst
index 914e5bc..49459f3 100644
--- a/docs/api.rst
+++ b/docs/api.rst
@@ -110,6 +110,7 @@ These tools combine multiple iterables.
 .. autofunction:: dotproduct
 .. autofunction:: flatten
 .. autofunction:: roundrobin
+.. autofunction:: prepend
 
 
 Summarizing
diff --git a/more_itertools/recipes.py b/more_itertools/recipes.py
index ec5e756..3a7706c 100644
--- a/more_itertools/recipes.py
+++ b/more_itertools/recipes.py
@@ -33,6 +33,7 @@ __all__ = [
     'pairwise',
     'partition',
     'powerset',
+    'prepend',
     'quantify',
     'random_combination_with_replacement',
     'random_combination',
@@ -548,3 +549,17 @@ def nth_combination(iterable, r, index):
         result.append(pool[-1 - n])
 
     return tuple(result)
+
+
+def prepend(value, iterator):
+    """Yield *value*, followed by the elements in *iterator*.
+
+        >>> value = '0'
+        >>> iterator = ['1', '2', '3']
+        >>> list(prepend(value, iterator))
+        ['0', '1', '2', '3']
+
+    To prepend multiple values, see :func:`itertools.chain`.
+
+    """
+    return chain([value], iterator)
diff --git a/more_itertools/tests/test_recipes.py b/more_itertools/tests/test_recipes.py
index f6d7680..81721fd 100644
--- a/more_itertools/tests/test_recipes.py
+++ b/more_itertools/tests/test_recipes.py
@@ -589,3 +589,19 @@ class NthCombinationTests(TestCase):
         actual = mi.nth_combination(range(180), 4, 2000000)
         expected = (2, 12, 35, 126)
         self.assertEqual(actual, expected)
+
+
+class PrependTests(TestCase):
+    def test_basic(self):
+        value = 'a'
+        iterator = iter('bcdefg')
+        actual = list(mi.prepend(value, iterator))
+        expected = list('abcdefg')
+        self.assertEqual(actual, expected)
+
+    def test_multiple(self):
+        value = 'ab'
+        iterator = iter('cdefg')
+        actual = tuple(mi.prepend(value, iterator))
+        expected = ('ab',) + tuple('cdefg')
+        self.assertEqual(actual, expected)
-- 
2.39.0.windows.2