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diff --git a/code/cartalk1.py b/code/cartalk1.py
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diff --git a/code/most_frequent.py b/code/most_frequent.py
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diff --git a/code/pace_calc.py b/code/pace_calc.py
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diff --git a/code/palindrome_soln.py b/code/palindrome_soln.py
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diff --git a/code/pi.py b/code/pi.py
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index bc9e7e1..d13609f
--- a/code/pi.py
+++ b/code/pi.py
@@ -1,3 +1,4 @@
+#!/usr/local/bin/python3
 """This module contains a code example related to
 
 Think Python, 2nd Edition
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