diff --git a/06_address_spaces.py b/06_address_spaces.py
new file mode 100644
index 0000000..e69de29
diff --git a/07_printf.py b/07_printf.py
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index 0000000..e69de29
diff --git a/06_mergesort.py b/08_mergesort.py
similarity index 100%
rename from 06_mergesort.py
rename to 08_mergesort.py
diff --git a/07_mergesort_speed.py b/09_mergesort_speed.py
similarity index 100%
rename from 07_mergesort_speed.py
rename to 09_mergesort_speed.py
diff --git a/08_image.py b/10_image.py
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rename from 08_image.py
rename to 10_image.py