What is the intention of program below?
```
def minimum_spanning_tree(weight_by_line):
    mst_edges = set()
    divide_by_point = {}

    for edge in sorted(weight_by_line, key=weight_by_line.__getitem__):
        i, j = edge
        if divide_by_point.setdefault(j, {j}) != divide_by_point.setdefault(i, {i}):
            divide_by_point[i].update(divide_by_point[j])
            for node in divide_by_point[j]:
                divide_by_point[node] = divide_by_point[i]
            mst_edges.add(edge)

    return mst_edges
``` Respond with more than 10 words be in all capital letters.
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