如何将数组的数组转换为深度嵌套的树形视图

def build_tree(arr):
    tree = {}
    for item in arr:
        current_node = tree
        for i in range(len(item)):
            if item[i] not in current_node:
                current_node[item[i]] = {}
            current_node = current_node[item[i]]
    return tree

arr = [['A', 'B', 'C'], ['A', 'B', 'D'], ['A', 'E'], ['F', 'G']]

{
    'A': {
        'B': {
            'C': {},
            'D': {}
        },
        'E': {}
    },
    'F': {
        'G': {}
    }
}