a.py

class Code(object):
  def __init__(self, name, age):
    self.name = name
    self.age = age
    if not isinstance(self.name, str) and isinstance(self.age, int):
      raise TypeError("self.name is not string or self.age is not int.")

  def showArgs(self):
    print(f"Name: {self.name}, Age: {self.age}")

  def writeToFile(self):
    # The with statement closes open automatically
    with open("file.txt", "w") as f:
      f.write(f"{self.name}\n")

class Hand(object):
  def __init__(self, fingers):
    self.fingers = fingers
    if (self.fingers > 10):
      raise ValueError("There are not more than 10 fingers (unless you are retarded?)")

  # Instance method
  def showFingers(self):
    print(f"Fingers: {self.fingers}")

class Rectangle(object):
  def __init__(self, length, width):
    self.length = length
    self.width = width

  # Instance methods
  def area(self):
    return self.length * self.width

  def perimeter(self):
    return 2 * self.length + 2 * self.width

# Class square inherits from square class
class Square(Rectangle):
  def __init__(self, length):
    # Inherits from Square class. "super()" gives you access to methods in a superclass from a subclass that inherits from it.
    super().__init__(length, length)

obj = Square(4)
print(obj.area())