def build_kwargs_read(spec: dict, ext: str) -> dict:
    """Builds up kwargs for the Pandas read_* functions."""
    col_arg_names = {'.parquet': 'columns',
                     '.xls': 'usecols',
                     '.xlsx': 'usecols',
                     '.csv': 'usecols'}
    kwargs = {}
    if 'columns' in list(spec['input'].keys()):
        kwargs[col_arg_names[ext]] = list(spec['input']['columns'].keys())

    return kwargs