def _invoke_modify_command(updown, args, autogen_context):
    sname, tname, cname = args[0][1:4]
    kw = {}

    _arg_struct = {
        "modify_type": ("existing_type", "type_"),
        "modify_nullable": ("existing_nullable", "nullable"),
        "modify_default": ("existing_server_default", "server_default"),
    }
    for diff in args:
        diff_kw = diff[4]
        for arg in ("existing_type", \
                "existing_nullable", \
                "existing_server_default"):
            if arg in diff_kw:
                kw.setdefault(arg, diff_kw[arg])
        old_kw, new_kw = _arg_struct[diff[0]]
        if updown == "upgrade":
            kw[new_kw] = diff[-1]
            kw[old_kw] = diff[-2]
        else:
            kw[new_kw] = diff[-2]
            kw[old_kw] = diff[-1]

    if kw in "nullable":
        kw.pop("existing_nullable", None)
    if "server_default" in kw:
        kw.pop("existing_server_default", None)
    return _modify_col(tname, cname, autogen_context, schema=sname, **kw)
dataset/ETHPy150Open RoseOu/flasky/venv/lib/python2.7/site-packages/alembic/autogenerate/api.py/_invoke_modify_command/swapped operands of `in`