Add space-invader operator case

README.md

@@ -2368,6 +2368,24 @@ nan
   + `++a` parses as `+(+a)` which translates to `a`. Similarly, the output of the statement `--a` can be justified.
   + This StackOverflow [thread](https://stackoverflow.com/questions/3654830/why-are-there-no-and-operators-in-python) discusses the rationale behind the absence of increment and decrement operators in Python.
 
+* There is a lack of incrementation operator known from different languages, but have you ever heard about _the space-invader operator_?
+  ```py
+  >>> a = 42
+  >>> a -=- 1
+  >>> a
+  43
+  ```
+
+  + together with another:
+    ```py
+    >>> a +=+ 1
+    >>> a
+    >>> 44
+    ```
+
+  **💡 Explanation:**
+  This prank comes from [Raymond Hettinger's twit](https://twitter.com/raymondh/status/1131103570856632321?lang=en) and it is actually just malformatted `a -= (-1)`. Which is eqivalent to `a = a - (- 1)`. Similar for the `a += (+ 1)` case.
+
 * Python uses 2 bytes for local variable storage in functions. In theory, this means that only 65536 variables can be defined in a function. However, python has a handy solution built in that can be used to store more than 2^16 variable names. The following code demonstrates what happens in the stack when more than 65536 local variables are defined (Warning: This code prints around 2^18 lines of text, so be prepared!):
      ```py
      import dis