queues.py

class Queue:
    def __init__(self):
        self.queue = []

    def enqueue(self, item):
        self.queue.append(item)

    def dequeue(self):
        if not self.is_empty():
            return self.queue.pop(0)
        return "Queue is empty"

    def is_empty(self):
        return len(self.queue) == 0

    def peek(self):
        return self.queue[0] if not self.is_empty() else None

    def size(self):
        return len(self.queue)

# Example Usage
q = Queue()
q.enqueue(10)
q.enqueue(20)
print(q.dequeue())  # Output: 10
print(q.peek())     # Output: 20