Add membership commands in comands topic

content/python/concepts/operators/operators.md

@@ -88,4 +88,8 @@ Python evaluates an expression in order of precedence as follows:
 - `and`
 - `or`
 
+## Membership operators
+- The `in` operator returns `True` if the element on the right _contains_ the element in the left. Here, the element on the right side of the `in` operator must be an iterable object like a list, string, dictionary, etc.
+- The `not in` operator returns `False` if the element on the right _does not contain_ the element on the left. Again, the element on the right side of the ` not in` operator must be an iterable object.
+
 **Note:** Items at the same precedence are evaluated left to right. The exception to this is exponentiation, which evaluates right to left.