Format lists in Sublime exactly the way I like it.

example_use.gif

sublime_format_list_one_item_per_line_plugin.py

import sublime_plugin


class FormatListOneLinePerItemCommand(sublime_plugin.TextCommand):
    """Format a one-line list/tuple into one-item-per-line.

    E.g. from:

        list_display = ("name", "kind", "parent",)

    to:

        list_display = (
            "name",
            "kind",
            "parent",
        )

    Keeps original indentation level and adds one level to items.
    Handles trailing comma/no trailing comma, but not much else.

    """
    def run(self, edit,
            split_pattern=",",
            remove_empty=True,
            indent_char=" "):
        view = self.view

        cursors = view.sel()
        if len(cursors) != 1:
            return

        view.run_command("expand_selection", args={"to": "brackets"})
        cursor = cursors[0]

        line = view.line(cursor)
        line_str = view.substr(line)
        indent = len(line_str) - len(line_str.lstrip())
        offset = indent_char * indent
        offset_border = offset
        offset_inner = offset + (indent_char * 4)

        region = cursor
        content = view.substr(region)
        parts = [part.strip() for part in content.split(split_pattern)
                 if not remove_empty or part.strip() != ""]

        new_content = "\n" + offset_inner
        new_content += "{}\n{}".format(split_pattern,
                                       offset_inner).join(parts)
        new_content += split_pattern + "\n" + offset_border

        view.replace(edit, region, new_content)