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+"""isort/natural.py.
+
+Enables sorting strings that contain numbers naturally
+
+usage:
+    natural.nsorted(list)
+
+Copyright (C) 2013  Timothy Edmund Crosley
+
+Implementation originally from @HappyLeapSecond stack overflow user in response to:
+   http://stackoverflow.com/questions/5967500/how-to-correctly-sort-a-string-with-a-number-inside
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated
+documentation files (the "Software"), to deal in the Software without restriction, including without limitation
+the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and
+to permit persons to whom the Software is furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all copies or
+substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
+TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
+CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+OTHER DEALINGS IN THE SOFTWARE.
+
+"""
+import re
+
+
+def _atoi(text):
+    return int(text) if text.isdigit() else text
+
+
+def _natural_keys(text):
+    return [_atoi(c) for c in re.split('(\d+)', text)]
+
+
+def nsorted(to_sort, key=None):
+    """Returns a naturally sorted list"""
+    if not key:
+        key_callback = _natural_keys
+    else:
+        key_callback = lambda item: _natural_keys(key(item))
+
+    return sorted(to_sort, key=key_callback)