From ce04aedaaa6b7cb9e34dcd2486d3ad1390407b8f Mon Sep 17 00:00:00 2001
From: Pietro Battiston <me@pietrobattiston.it>
Date: Sun, 20 Aug 2017 19:38:52 +0200
Subject: [PATCH] Comment

---
 pandas/core/dtypes/concat.py | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/pandas/core/dtypes/concat.py b/pandas/core/dtypes/concat.py
index 0bb8d0021c6cfe..dd7bd3b6cad1dc 100644
--- a/pandas/core/dtypes/concat.py
+++ b/pandas/core/dtypes/concat.py
@@ -565,6 +565,11 @@ def convert_sparse(x, axis):
 
 
 def _concat_indexes_same_dtype_rangeindex(indexes):
+    # Concatenates multiple RangeIndex instances. All members of "indexes" must
+    # be of type RangeIndex; result will be RangeIndex if possible, Int64Index
+    # otherwise. E.g.:
+    # indexes = [RangeIndex(3), RangeIndex(3, 6)] -> RangeIndex(6)
+    # indexes = [RangeIndex(3), RangeIndex(4, 6)] -> Int64Index([0,1,2,4,5])
 
     start = step = next = None