def represent_list(self, data):
        node = super(Dumper, self).represent_list(data)
        length = len(data)
        if self.default_flow_style is None and length < 4:
            node.flow_style = True
        elif self.default_flow_style is None:
            node.flow_style = False
        return node
If a list has less than 4 items, represent it in inline style
dataset/ETHPy150Open beetbox/beets/beets/util/confit.py/Dumper.represent_list