London | 2026-mar-sdc | beko | Sprint 5 | prep exercises

prep exercises/checking_mypy.py

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+
+
+def open_account(balances: dict[str, int], name: str, amount: int) -> None:
+    balances[name] = amount
+
+def sum_balances(accounts: dict[str, int]) -> int:
+    total = 0
+    for name, pence in accounts.items():
+        print(f"{name} had balance {pence}")
+        total += pence
+    return total
+
+def format_pence_as_string(total_pence: int) -> str:
+    if total_pence < 100:
+        return f"{total_pence}p"
+    pounds = int(total_pence / 100)
+    pence = total_pence % 100
+    return f"£{pounds}.{pence:02d}"
+
+balances: dict[str, int] = {
+    "Sima": 700,
+    "Linn": 545,
+    "Georg": 831,
+}
+
+open_account(balances, "Tobi", 913)
+open_account(balances, "Olya", 713)
+
+total_pence = sum_balances(balances)
+total_string = format_pence_as_string(total_pence)
+
+print(f"The bank accounts total {total_string}")

prep exercises/dataclass.py

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+
+
+from dataclasses import dataclass
+from datetime import date
+
+@dataclass(frozen=True)
+class Person:
+      name: str
+      birth_day: date
+      preferred_OS: str
+
+
+      def is_adult(self):
+            today = date.today()
+            age = today.year - self.birth_day.year
+
+            if (today.month, today.day) < (self.birth_day.month, self.birth_day.day):
+                  age -= 1
+            return age >= 18
+
+
+beko = Person("Beko", date(2005, 2, 17), "Linux")
+print(beko.is_adult())
+
+noor = Person("Noor", date(2015, 2, 17), "Linux")
+print(noor.is_adult())

prep exercises/double.py

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+
+def double (num):
+      return num * 2
+
+print(double("22"))
+
+# Predication
+# Did it do what you expected? 
+#  No, it didn't
+# 
+# Why did it return the value it did? 
+# because there is a mistype in the function, it should take a number but the argument is string 
+# 
+
+def double_the_number(num):
+      return num * 3
+
+print(double_the_number(5))

prep exercises/enums.py

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+from dataclasses import dataclass
+from enum import Enum
+from typing import List
+import sys
+
+
+class OperatingSystem(Enum):
+    MACOS = "macOS"
+    ARCH = "Arch Linux"
+    UBUNTU = "Ubuntu"
+
+
+@dataclass(frozen=True)
+class Person:
+    name: str
+    age: int
+    preferred_operating_system: OperatingSystem
+
+
+@dataclass(frozen=True)
+class Laptop:
+    id: int
+    manufacturer: str
+    model: str
+    screen_size_in_inches: float
+    operating_system: OperatingSystem
+
+
+# Existing inventory list
+laptops = [
+    Laptop(
+        id=1,
+        manufacturer="Dell",
+        model="XPS",
+        screen_size_in_inches=13,
+        operating_system=OperatingSystem.ARCH,
+    ),
+    Laptop(
+        id=2,
+        manufacturer="Dell",
+        model="XPS",
+        screen_size_in_inches=15,
+        operating_system=OperatingSystem.UBUNTU,
+    ),
+    Laptop(
+        id=3,
+        manufacturer="Dell",
+        model="XPS",
+        screen_size_in_inches=15,
+        operating_system=OperatingSystem.UBUNTU,
+    ),
+    Laptop(
+        id=4,
+        manufacturer="Apple",
+        model="macBook",
+        screen_size_in_inches=13,
+        operating_system=OperatingSystem.MACOS,
+    ),
+]
+
+
+def get_user_input() -> Person:
+    name = input("Enter your name: ").strip()
+    if not name:
+        print("Error: Name cannot be empty.", file=sys.stderr)
+        sys.exit(1)
+
+    # 1. check the person's age is valid
+    try:
+        age = int(input("Enter your age: "))
+        if age < 0:
+            raise ValueError
+    except ValueError:
+        print("Error: Age must be a positive whole number.", file=sys.stderr)
+        sys.exit(1)
+
+    # 2. give the person a list of valid Operating Systems to choose from
+    print("\nAvailable Operating Systems:")
+    for os_option in OperatingSystem:
+        print(f"- {os_option.value}")
+
+    os_input = input("Enter your preferred operating system: ").strip()
+
+    # Try to match the user string to a valid Enum value
+    preferred_os = None
+    for os_option in OperatingSystem:
+        if os_option.value.lower() == os_input.lower():
+            preferred_os = os_option
+            break
+
+    if preferred_os is None:
+        print(f"Error: '{os_input}' is not a valid operating system.", file=sys.stderr)
+        sys.exit(1)
+
+    return Person(name=name, age=age, preferred_operating_system=preferred_os)
+
+
+def main():
+    # Get valid user data
+    user = get_user_input()
+
+    # Count laptops for each operating system
+    os_counts = {os_type: 0 for os_type in OperatingSystem}
+    for laptop in laptops:
+        os_counts[laptop.operating_system] += 1
+
+    # Look up counts for user choice and find the maximum available
+    user_os = user.preferred_operating_system
+    user_os_count = os_counts[user_os]
+
+    most_available_os = max(os_counts, key=os_counts.get)
+    max_count = os_counts[most_available_os]
+
+    # Output results
+    print(f"\nHello {user.name}!")
+    print(f"The library has {user_os_count} laptop(s) running {user_os.value}.")
+
+    # Suggest alternative if another OS has more stock
+    if max_count > user_os_count:
+        print(
+            f"💡 Tip: If you choose {most_available_os.value}, we have {max_count} laptops available. You're more likely to get one quickly!"
+        )
+
+
+if __name__ == "__main__":
+    main()

prep exercises/generics.py

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+from dataclasses import dataclass
+from typing import List
+
+@dataclass(frozen=True)
+class Person:
+    name: str
+    age: int
+    children: List["Person"]
+
+fatma = Person(name="Fatma", age=10, children=[])
+aisha = Person(name="Aisha", age=15, children=[])
+
+imran = Person(name="Imran", age=40, children=[fatma, aisha])
+
+def print_family_tree(person: Person) -> None:
+    print(person.name)
+    for child in person.children:
+        print(f"- {child.name} ({child.age})")
+
+print_family_tree(imran)

prep exercises/inheritance.py

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+
+
+class Parent:
+    def __init__(self, first_name: str, last_name: str):
+        self.first_name = first_name
+        self.last_name = last_name
+
+    def get_name(self) -> str:
+        return f"{self.first_name} {self.last_name}"
+
+
+class Child(Parent):
+    def __init__(self, first_name: str, last_name: str):
+        super().__init__(first_name, last_name)
+        self.previous_last_names = []
+
+    def change_last_name(self, last_name) -> None:
+        self.previous_last_names.append(self.last_name)
+        self.last_name = last_name
+
+    def get_full_name(self) -> str:
+        suffix = ""
+        if len(self.previous_last_names) > 0:
+            suffix = f" (née {self.previous_last_names[0]})"
+        return f"{self.first_name} {self.last_name}{suffix}"
+
+
+
+person1 = Child("Elizaveta", "Alekseeva")
+# Predict: Creates a Child object. Works perfectly.
+
+print(person1.get_name())
+# Predict: it will print "Elizaveta Alekseeva" 
+# Child inherits this method from Parent
+
+print(person1.get_full_name())
+#  Predict: it will print "Elizaveta Alekseeva" because the last name has not been changed yet.
+# get_full_name is defined in Child, but it uses the last name from Parent, which is "Alekseeva" at this point.
+
+person1.change_last_name("Tyurina")
+#  Predict: Changes last_name to "Tyurina" and saves "Alekseeva" in the
+# previous_last_names list. Works perfectly.
+
+print(person1.get_name())
+# Predict: Prints "Elizaveta Tyurina". 
+# get_name is inherited from Parent, but it uses the updated last name "Tyurina".
+
+print(person1.get_full_name())
+# Predict: Prints "Elizaveta Tyurina (née Alekseeva)".
+# get_full_name uses the updated last name "Tyurina" and also includes the previous last name "Alekseeva" in the output.
+print()
+
+person2 = Parent("Elizaveta", "Alekseeva")
+# Predict: Creates a Parent object. Works perfectly.
+
+print(person2.get_name())
+# Predict: it will print "Elizaveta Alekseeva"
+# get_name is defined in Parent, so it works perfectly.
+
+print(person2.get_full_name())
+# Predict: it will raise an AttributeError because get_full_name is not defined in Parent, 
+# and Parent does not have access to the methods of Child.
+
+person2.change_last_name("Tyurina")
+# Predict: it will raise an AttributeError because change_last_name is not defined in Parent,
+# and Parent does not have access to the methods of Child.
+
+print(person2.get_name())
+# Predict: it will print "Elizaveta Alekseeva" because the last name has not been changed due to the previous error.
+
+print(person2.get_full_name())
+# Predict: it will raise an AttributeError again for the same reason as before.

prep exercises/methods.py

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+from datetime import date
+
+
+class Person:
+    def __init__(self, name: str, date_of_birth: date, preferred_operating_system: str, favorite_sport: str) -> None:
+        self.name = name
+        self.date_of_birth = date_of_birth
+        self.preferred_operating_system = preferred_operating_system
+        self.favorite_sport = favorite_sport
+
+    def is_adult(self):
+        today = date.today()
+        age = today.year - self.date_of_birth.year
+
+        birthday_passed = (
+              (today.month, today.day) >= (self.date_of_birth.month, self.date_of_birth.day)
+        )
+        if not birthday_passed:
+            age -= 1
+        return age >= 18
+
+
+
+beko = Person("Beko", date(2005, 2, 17), "Linux", "Football")
+print(beko.is_adult())
+
+
+# Advantages of methods over free functions:
+
+# Keep data and behavior together: 
+# A method belongs directly to an object. It combines the object's info (data) and actions (behavior) into one package
+
+# Make code easier to read: 
+# You call them using object.action(). This reads like a normal sentence, making the code self-explanatory.  
+# same (imran.is_adult() is easier to understand than is_adult(imran))
+
+# Support inheritance: 
+# Child objects automatically get access to the parent's methods. This means you do not have to copy and paste code.
+
+# Enable polymorphism: 
+# Different objects can use the exact same method name but handle it in their own unique way 
+# (like a Dog and a Cat both responding to a .makeSound() method)

prep exercises/person_class.py

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+
+
+
+class Person:
+    def __init__(self, name: str, age: int, preferred_operating_system: str, favorite_sport: str) -> None:
+        self.name = name
+        self.age = age
+        self.preferred_operating_system = preferred_operating_system
+        self.favorite_sport = favorite_sport
+
+    def is_adult(self) -> bool:
+          return self.age >= 18
+
+    def get_favorite_sport(self) -> str:
+          return self.favorite_sport
+
+
+
+imran = Person("Imran", 22, "Ubuntu", "Football")
+print(imran.name)
+print(imran.is_adult())
+print(imran.preferred_operating_system)
+print(imran.get_favorite_sport())
+
+eliza = Person("Eliza", 34, "Arch Linux", "Tennis")
+print(eliza.name)
+print(eliza.is_adult())
+print(eliza.preferred_operating_system)
+print(eliza.get_favorite_sport())