Create expression precendence level

smnp/ast/node/valuable.py

@@ -0,0 +1,22 @@
+from smnp.ast.node.model import Node
+from smnp.ast.node.none import NoneNode
+
+
+class Valuable(Node):
+    def __init__(self, pos):
+        super().__init__(pos)
+        self.children = [NoneNode()]
+
+    @property
+    def value(self):
+        return self[0]
+
+    @value.setter
+    def value(self, value):
+        self[0] = value
+
+    @classmethod
+    def withValue(cls, value):
+        node = cls(value.pos)
+        node.value = value
+        return node