Modify rule S2583: Migrate Python description to LaYC format (#3198)

rules/S2583/python/rule.adoc

@@ -1,23 +1,70 @@
+Conditional expressions which are always `true` or `false` can lead to https://en.wikipedia.org/wiki/Unreachable_code[unreachable code].
+To fix this issue, either update the condition or remove the unreachable code.
+
 == Why is this an issue?
 
-include::../description.adoc[]
+Unreachable code is never executed, so it has no effect on the behaviour of the program.
+If it is not executed because it no longer serves a purpose, then it adds unnecessary complexity.
+Otherwise, it indicates that there is a logical error in the condition.
+
+=== What is the potential impact?
+
+Unreachable code affects maintainability.
+It is harder for programmers to read, understand and modify the code when some parts are unreachable.
+If the code should be reachable instead, then the program may not always behave as intended.
+
+=== Exceptions
+
+This rule will not raise an issue when
+
+* The condition to reach the dead code is a boolean literal.
+* The unreachable code is a simple statement, such as `pass`.
+
+== How to fix it
+
+You should first decide whether the unreachable code is useful.
+If it is, then you should understand why the condition that leads to it is always false, and correct logical errors.
+Otherwise, the code should be removed along with the condition.
+
+=== Code examples
 
-=== Noncompliant code example
+==== Noncompliant code example
 
-[source,python]
+[source,python,diff-id=1,diff-type=noncompliant]
 ----
-a = False
-if a:  # Noncompliant
-    doSomething()  # never executed
+def foo(a, b):
+    flag = True
 
-n = None
+    if (a and not a):  # Noncompliant
+        doSomething()  # Never executed
 
-if not n:  # Noncompliant; n is None, which is always equivalent to "False" in a condition, "doSomethingElse()" is never evaluated
-    doSomething()
-else:
-    doSomethingElse()  # never executed
+    if (flag): # Noncompliant
+        return "Result 1"
+    return "Result 2" # Never executed
 ----
 
+==== Compliant solution
+
+[source,python,diff-id=1,diff-type=compliant]
+----
+def foo(a, b):
+    if (a and not b):
+        doSomething()
+
+    return "Result 1"
+----
+
+=== How does this work?
+
+The first condition is always false.
+In this case, we decide that the call to `doSomething` is useful.
+The problem is then a bug in the condition; for example, using `a` instead of `b`.
+
+The second condition is always true.
+Here, we decided that the second return statement is not useful anymore.
+There may have been code manipulating the variable `flag` that was previously removed.
+We can remove the unreachable code, the condition and the variable.
+
 include::../see.adoc[]
 
 ifdef::env-github,rspecator-view[]