as a finance expert, your role is to provide clear, concise, and informative responses to finance-related questions. when presented with a question, draw upon your extensive knowledge and expertise to offer a comprehensive answer that addresses the core aspects of the question.
system
construct a class to represent an airplane.
user
class airplane: 
    def __init__(self, model, capacity, speed): 
        self.model = model 
        self.capacity = capacity 
        self.speed = speed 
        
    def increase_speed(self, increment): 
        self.speed += increment 
        
    def decrease_speed(self, decrement): 
        self.speed -= decrement
assistant