diff --git a/exercises/exerciseB/README.md b/exercises/exerciseB/README.md
index 40ab9e6..6728cc7 100644
--- a/exercises/exerciseB/README.md
+++ b/exercises/exerciseB/README.md
@@ -14,6 +14,7 @@ relative differences between the analytic result and the numerical result
 for different values of the number of steps.
 
 **TASKS**:  
+
  0. Read `numerical_integration.py` and familiarize yourselves with the code.
  1. Update the `main` function so that it calculates the numerical error without
     any parallelization. You can use a for loop or `map`.
@@ -23,5 +24,6 @@ for different values of the number of steps.
     What speed-up did you get?
 
 **BONUS TASKS (very optional)**:  
+
  5. Implement a parallel version with threads (using `multiprocessing.pool.ThreadPool`).
  6. Time this version, and hypothetize about the result.
diff --git a/exercises/exerciseB/map_example_codealong.py b/exercises/exerciseB/map_example_codealong.py
new file mode 100644
index 0000000..b07d6a4
--- /dev/null
+++ b/exercises/exerciseB/map_example_codealong.py
@@ -0,0 +1,40 @@
+# Computer scientists love the Fibonacci sequence
+# [https://en.wikipedia.org/wiki/Fibonacci_sequence], possibly
+# described by Acharya Pingala in छन्दःशास्त्र (Chhandaḥśāstra).
+#
+# The basic definition is that the next item in the sequence
+# if the sum of the two preceding items, and the two initial
+# items and 0 and 1.
+#
+# We end up with [0, 1, 1, 2, 3, 5, 8, 13, ...]
+
+def fibbo(n):
+    match n:
+        case 0 | 1:
+            return n
+        case _:
+            return fibbo(n-1) + fibbo(n-2)
+
+# For example: the first few items in the sequence:
+for n in range(36):
+    print(n, fibbo(n))
+
+# A (nowadays) less commonly used way to construct the mapping
+# from n to fibbo(n) is to use the map function.
+# map returns a generator, and we call list to collect the numbers:
+sequence = list(map(fibbo, range(36)))
+print(sequence)
+
+# To split the work between multiple Python processes, we can
+# use the multiprocessing module:
+import multiprocessing
+
+pool = multiprocessing.Pool()
+sequence = pool.map(fibbo, range(36))
+print(sequence)
+
+# We may use 'with' to clean up the pool after we're done with
+# the workers:
+with multiprocessing.Pool(10) as pool:
+    sequence = pool.map(fibbo, range(36))
+print(sequence)
diff --git a/exercises/exerciseC/run_with_all_configurations.sh b/exercises/exerciseC/run_with_all_configurations.sh
old mode 100644
new mode 100755
index 30a1414..ffe1012
--- a/exercises/exerciseC/run_with_all_configurations.sh
+++ b/exercises/exerciseC/run_with_all_configurations.sh
@@ -1,9 +1,13 @@
-# This is bash
-# It runs the python script multiple times with different arguments
+#!/bin/bash
+set -ex
+
+# This is a bash script.
+# It runs the python program multiple times with different arguments.
+
 for i in {1..5}  # Number of processes
 do
     for j in {1..5}  # Number of threads
     do
         python process_images.py $i $j images/*
     done
-done
\ No newline at end of file
+done
diff --git a/slides/map_example_codealong.py b/slides/map_example_codealong.py
new file mode 120000
index 0000000..7e35e80
--- /dev/null
+++ b/slides/map_example_codealong.py
@@ -0,0 +1 @@
+../exercises/exerciseB/map_example_codealong.py
\ No newline at end of file