from dataclasses import dataclass

@dataclass
class Shape:
    """Base class for shapes"""
    def area(self):
        raise NotImplementedError

@dataclass
class Circle(Shape):
    """Circle shape"""
    radius: float

    def area(self):
        """Calculate the area of the circle"""
        return 3.14 * (self.radius ** 2)

@dataclass
class Rectangle(Shape):
    """Rectangle shape"""
    width: float
    height: float

    def area(self):
        """Calculate the area of the rectangle"""
        return self.width * self.height