reorganize dir

Signed-off-by: Mia Steinkirch <mia.steinkirch@gmail.com>

ebook_src/builtin_structures/reverse_string.py

@@ -0,0 +1,37 @@
+#!/usr/bin/env python
+
+__author__ = "bt3"
+
+
+def revert(string):
+    '''
+    >>> s = 'hello'
+    >>> revert(s)
+    'olleh'
+    >>> revert('')
+    ''
+    '''
+    return string[::-1]
+
+
+
+def reverse_string_inplace(s):
+    '''
+    >>> s = 'hello'
+    >>> reverse_string_inplace(s)
+    'olleh'
+    >>> reverse_string_inplace('')
+    ''
+    '''
+    if s:
+        s = s[-1] + reverse_string_inplace(s[:-1])
+    return s
+
+
+
+
+
+
+if __name__ == '__main__':
+    import doctest
+    doctest.testmod()