Add a file showing the use of global variables in functions

Python/029_scope.py

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+# Scope of variables
+
+# As mentioned before, the "scope" of something is just
+# "where can this thing be accessed".
+
+# More detailed reading about scope: https://realpython.com/python-scope-legb-rule/
+
+# Highly Recommended: Details about Mutable vs. Immutable
+# https://realpython.com/python-mutable-vs-immutable-types/
+
+# Let's declare a couple global variables
+MAX_TEACHERS = 30
+MAX_STUDENTS_PER_TEACHER = 25
+
+# Let's create a couple functions to get values
+
+# This function makes use of the MAX_TEACHERS global variable
+def get_teacher_count():
+    count = 0
+    while count == 0:
+        # Get a value from the user
+        response = input(f"How many teachers at the school (1-{MAX_TEACHERS})? ")
+        # If response is just a number
+        if response.isdigit():
+            # Convert to an int
+            count = int(response)
+            # If count is out of range, show an error and reset count
+            if count == 0 or count > MAX_TEACHERS:
+                print(f"   Error: Number of teachers must be greater than zero and no greater than {MAX_TEACHERS}!")
+                count = 0
+        # Otherwise show an error
+        else:
+            print(f"   Error: Please enter a value between 1 and {MAX_TEACHERS}!")
+    return count
+
+# This function makes use of the MAX_STUDENTS_PER_TEACHER global variable
+# and is passed the number of teachers obtained from get_teacher_count()
+def get_student_count(teacher_count: int):
+    count = 0
+    # Can't have fewer students than teachers
+    min_students = teacher_count
+    # Can't have more than MAX_STUDENTS_PER_TEACHER average
+    max_students = teacher_count * MAX_STUDENTS_PER_TEACHER
+    while count == 0:
+        response = input(f"How many students at the school ({min_students}-{max_students})? ")
+        if response.isdigit():
+            count = int(response)
+            if count < min_students or count > max_students:
+                print(f"   Error: Number of teachers must be between {min_students} and {max_students}!")
+                count = 0
+        else:
+            print(f"   Error: Please enter a value between {min_students} and {max_students}!")
+    return count
+
+# Some program logic
+teachers = get_teacher_count()
+students = get_student_count(teachers)
+print()
+print(f"Teachers: {teachers}")
+print(f"Students: {students}")
+print("Average class size: " + str(students // teachers))