def form_indent(eval_ctx, num: int) -> str:
    """Form an indentation space block.

    Parameters
    ----------

    eval_ctx
        The evaluation context.
    num
        The number of the indentation. The size of the indentation is going to
        be read from the context by attribute ``indent_size``.

    Return
    ------

    A block of white spaces.

    """

    return ' ' * (
        eval_ctx['indent_size'] * (num + eval_ctx['global_indent'])
    )