diff --git a/build.py b/build.py
index e69de29..2834a31 100644
--- a/build.py
+++ b/build.py
@@ -0,0 +1,20 @@
+def is_rotation(src,dest):
+    """ here a string s1 is a rotation of another string s2,
+     by calling (only once) a function is_rotation """
+
+    if(src == None or dest == None):
+        return False
+    elif(src == "" and dest == ""):
+        return True
+    elif(src == "" and dest != ""):
+        return False
+    elif(src != "" and dest == ""):
+        return False
+    else:
+        if(len(src) != len(dest)):
+            return False
+
+        for i in range(len(src)):
+             if dest.startswith(src[i:]) and dest.endswith(src[:i]):
+                 return True
+        return False
diff --git a/build.pyc b/build.pyc
new file mode 100644
index 0000000..7d83b83
Binary files /dev/null and b/build.pyc differ
diff --git a/tests/__init__.pyc b/tests/__init__.pyc
new file mode 100644
index 0000000..3083b23
Binary files /dev/null and b/tests/__init__.pyc differ
diff --git a/tests/test_is_rotation.pyc b/tests/test_is_rotation.pyc
new file mode 100644
index 0000000..16ee8ef
Binary files /dev/null and b/tests/test_is_rotation.pyc differ