Short circuiting done

Basic/prog.py

@@ -0,0 +1 @@
+print(bool(None))

Basic/wiki.txt

@@ -81,6 +81,8 @@
     provide the new overrided value instead of previous value.
     Hence, key of Dictionary should be unique
 
+    tuple can be used as key for Dictionary but not list.
+    
 -> list and tuple:
 
     list are mutable but tuple are immutable
@@ -91,3 +93,48 @@
     might result in error, but to avoid that we can use
     methods instead of keyword for accessing any value
     and avoiding error.
+
+-> difference_update method in sets:
+
+    It is used to delete members which is present in set
+    which is passed as parameter to this method and the 
+    object which used this method having same elements 
+    as present in the set passed as parameter is removed
+    and the object set is modified.
+
+
+-> union and intersection operator of set:
+
+    union : |
+    intersection : &
+
+-> Truthy and falsey:
+
+    some value if their type is converted using
+    type() function.
+
+    Truthy: Conversion to True value from some value is a
+            Truthy value.
+
+    Falsey: Conversion to False value from some value is a
+            Falsey value.
+
+    For ex:
+
+        bool("hello") -> True (Truthy)
+        bool('')      -> False (Falsey)
+        bool(0)       -> False (Falsey)
+        bool(199)     -> True  (Truthy)
+
+-> Ternary Operator or conditional expression:
+
+    <statement_if_true> if <condition> else <statement_if_false>
+
+-> Short Circuiting:
+
+    true and true : Both are evaluated
+    false and true : first is evaluated
+    false and false : first is evaluated
+    true or true : first is evaluated
+    false or true : both are evaluated
+    false or false : both are evaluated