Added missing thing.

difftest.py

@@ -0,0 +1,44 @@
+import difflib
+
+s1 = "1234asdffooMOO"
+s2 = "asdfbarMOOwhatever"
+
+# s1 = "asdffoo"
+# s2 = "asdffooMOO"
+
+def onestepchange(start, dest):
+
+    ret = ""
+
+    for i, s in enumerate(difflib.ndiff(start, dest)):
+        # print(i)
+        # print(s)
+
+        if s[0] == '-':
+            return ret + start[i+1:]
+
+        if s[1] == '+':
+            return ret + s[-1] + start[i:]
+
+        ret = ret + s[-1]
+
+        if len(ret) > len(start):
+            return ret
+
+        if ret[i] != start[i]:
+            return ret + start[i:]
+
+    return ret
+
+
+n = s1
+while n != s2:
+    print(n)
+    n = onestepchange(n, s2)
+
+print(n)
+
+# for i, s in enumerate(difflib.ndiff(s1, s2)):
+#     print(i)
+#     print(s)
+