Generate a python program that has the following intention:

The intention of the program is to find the shortest path between a given start node and a destination node in a weighted graph, using a Fibonacci heap data structure.

The program uses the shortest_path_length function to find the shortest path length between the start node and the destination node. It does this by maintaining a Fibonacci heap (using the unknown_points list) containing pairs of nodes and their corresponding distances. The get function is used to retrieve the distance between a given node and the target node from the Fibonacci heap.

The insert_or_update function is used to insert or update a node's distance in the Fibonacci heap. It first checks if the node is already in the heap, and if it is, it updates the distance. Otherwise, it inserts the node with its distance into the heap.

The program starts by pushing the starting node and its distance of 0 into the Fibonacci heap. It then repeatedly pops the minimum distance and node from the heap and checks if the popped node is the destination node. If it is, the function returns the shortest path length.

If the destination node is not the popped node, the program iterates over its successors (neighboring nodes) and checks if they have already been visited. If not, it calculates the minimum distance from the successor to the destination node and inserts or updates the distance in the Fibonacci heap.

The program returns the shortest path length when the destination node is found, or float('inf') if no path exists. Please reply with exactly 4 paragraphs and separate each paragraph with two new lines. The very last paragraph must start with the word "several".
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