diff --git a/mapytex/calculus/core/MO/mo.py b/mapytex/calculus/core/MO/mo.py
index 7f01193..2770859 100644
--- a/mapytex/calculus/core/MO/mo.py
+++ b/mapytex/calculus/core/MO/mo.py
@@ -116,6 +116,15 @@ class MO(object):
         except AttributeError:
             return str(self.value)
 
+    def __hash__(self):
+        return self.value.__hash__()
+
+    def __eq__(self, other):
+        """ == a MOnumber """
+        try:
+            return self.value == other.value
+        except AttributeError:
+            return self.value == other
 
 @total_ordering
 class MOnumber(MO):
@@ -254,13 +263,6 @@ class MOnumber(MO):
         except AttributeError:
             return other % self.value
 
-    def __eq__(self, other):
-        """ == a MOnumber """
-        try:
-            return self.value == other.value
-        except AttributeError:
-            return self.value == other
-
     def __lt__(self, other):
         """ < a MOnumber """
         try:
@@ -268,8 +270,6 @@ class MOnumber(MO):
         except AttributeError:
             return self.value < other
 
-    def __hash__(self):
-        return self.value.__hash__()
 
 class MOstr(MO):
 
@@ -311,8 +311,13 @@ class MOstr(MO):
         if not val.isalpha():
             raise MOError(f"An MOstr should be initiate with a alpha string, got {val}")
 
-        MO.__init__(self, value)
+        MO.__init__(self, val)
         self.is_scalar = False
+        self._variable = val
+
+    @property
+    def variable(self):
+        return self._variable
 
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