def _set_by_path(tree, keys, value):
    'Set a value in a nested object in tree by sequence of keys.'
    keys = keys.split(';')
    _get_by_path(tree, keys[:(- 1)])[keys[(- 1)]] = value
Set a value in a nested object in tree by sequence of keys.
def _set_by_path(tree, keys, value):
    
    keys = keys.split(';')
    _get_by_path(tree, keys[:(- 1)])[keys[(- 1)]] = value