def _set_ax_config(ax, str_x_axis, str_y_axis, size_labels=32, size_ticks=
    22, xlim_min=None, xlim_max=None, is_box=True, is_zero_axis=False,
    is_grid=True):
    """
    It sets an axis configuration.

    :param ax: inputs for acquisition function. Shape: (n, d).
    :type ax: matplotlib.axes._subplots.AxesSubplot
    :param str_x_axis: the name of x axis.
    :type str_x_axis: str.
    :param str_y_axis: the name of y axis.
    :type str_y_axis: str.
    :param size_labels: label size.
    :type size_labels: int., optional
    :param size_ticks: tick size.
    :type size_ticks: int., optional
    :param xlim_min: None, or minimum for x limit.
    :type xlim_min: NoneType or float, optional
    :param xlim_max: None, or maximum for x limit.
    :type xlim_max: NoneType or float, optional
    :param is_box: flag for drawing a box.
    :type is_box: bool., optional
    :param is_zero_axis: flag for drawing a zero axis.
    :type is_zero_axis: bool., optional
    :param is_grid: flag for drawing grids.
    :type is_grid: bool., optional

    :returns: None.
    :rtype: NoneType

    """
    if str_x_axis is not None:
        ax.set_xlabel(str_x_axis, fontsize=size_labels)
    ax.set_ylabel(str_y_axis, fontsize=size_labels)
    ax.tick_params(labelsize=size_ticks)
    if not is_box:
        ax.spines['top'].set_color('none')
        ax.spines['right'].set_color('none')
    if xlim_min is not None and xlim_max is not None:
        ax.set_xlim([xlim_min, xlim_max])
    if is_zero_axis:
        ax.spines['bottom'].set_position('zero')
    if is_grid:
        ax.grid()
    return
