How to use the siuba.dply.verbs.VarList function in siuba

def var_create(*args):
    vl = VarList()
    all_vars = []
    for arg in args:
        if callable(arg) and not isinstance(arg, Var):
            all_vars.append(arg(vl))
        else:
            all_vars.append(arg)
     
    return all_vars

def _select(__data, *args, **kwargs):
    # see https://stackoverflow.com/questions/25914329/rearrange-columns-in-sqlalchemy-select-object
    if kwargs:
        raise NotImplementedError(
                "Using kwargs in select not currently supported. "
                "Use _.newname == _.oldname instead"
                )
    last_op = __data.last_op
    columns = {c.key: c for c in last_op.inner_columns}

    # same as for DataFrame
    colnames = Series(list(columns))
    vl = VarList()
    evaluated = (arg(vl) if callable(arg) else arg for arg in args)
    od = var_select(colnames, *evaluated)

    col_list = []
    for k,v in od.items():
        col = columns[k]
        col_list.append(col if v is None else col.label(v))

    return __data.append_op(last_op.with_only_columns(col_list))