Print a nice text tree of nested python objects.

print_tree.py

def print_tree(tree, prefix=[], last_prefix="", print_item=str):
    """
    Return a string where each line represents one item of tree.
    
    prefix and last_prefix are used internally.
    
    print_item: 
        The function applied to items in the tree. 
        Default `str`.
    
    Example:
    >>> print(print_tree(['f', [2, [22, 33], 3]]))
    ['f', [2, [22, 33], 3]]
    ├── 'f'
    └── [2, [22, 33], 3]
        ├── 2
        ├── [22, 33]
        │   ├── 22
        │   └── 33
        └── 3
    """
    s = "\n" + "".join(prefix[:-1]) + last_prefix + print_item(tree)
    try:
        last_i = len(tree) - 1
        if tree is tree[0]:
            return s  # avoid infinit recursion
        for i, item in enumerate(tree):
            if i == last_i:
                s += print_tree(item,
                                prefix=prefix + ["    "],
                                last_prefix="└── ",
                                print_item=print_item)
            else:
                s += print_tree(item,
                                prefix=prefix + ["│   "],
                                last_prefix="├── ",
                                print_item=print_item)
    except TypeError:
        pass
    return s