adding all files done so far

learning/descriptors/test.py

@@ -0,0 +1,16 @@
+class P(object):
+    def __init__(self, x):
+        self._x = x
+
+    @property
+    def x(self):
+        return self._x
+
+    @x.setter
+    def x(self, x):
+        if x < 0:
+            self._x = 0
+        elif x > 1000:
+            self._x = 1000
+        else:
+            self._x = x