Use current time as the default timestamp.

setup.py

@@ -10,7 +10,7 @@ def contents(*filenames):
 setup(
     name = "yangson",
     packages = ["yangson"],
-    version = "0.1.39",
+    version = "0.1.40",
     description = "Library for working with YANG schemas and data",
     author = "Ladislav Lhotka",
     author_email = "lhotka@nic.cz",

yangson/instance.py

@@ -14,12 +14,12 @@ Value = Union[ScalarValue, "ArrayValue", "ObjectValue"]
 class StructuredValue:
     """Abstract class for array and object values."""
 
-    def __init__(self, ts: datetime = None) -> None:
+    def __init__(self, ts: datetime) -> None:
         """Initialize class instance.
 
         :param ts: creation timestamp
         """
-        self.timestamp = ts
+        self.timestamp = ts if ts else datetime.now()
 
     def stamp(self) -> None:
         """Update the receiver's timestamp to current time."""

yangson/schema.py

@@ -313,7 +313,6 @@ class InternalNode(SchemaNode):
             if ch is None:
                 raise NonexistentSchemaNode(cn[0], cn[1] if cn[1] else self.ns)
             res[ch.instance_name()] = ch.from_raw(val[qn])
-        res.stamp()
         return res
 
     def _ascii_tree(self, indent: str) -> str:
@@ -445,7 +444,6 @@ class SequenceNode(DataNode):
         res = ArrayValue([])
         for en in val:
             res.append(self._entry_from_raw(en))
-        res.stamp()
         return res
 
     def _entry_from_raw(self, val: RawValue) -> Value: