How to use the astroplan.utils._set_mpl_style_sheet function in astroplan

Returns
    -------
    ax : `~matplotlib.axes.Axes`
        An ``Axes`` object with added airmass vs. time plot.

    Notes
    -----
    y-axis is inverted and shows airmasses between 1.0 and 3.0 by default.
    If user wishes to change these, use ``ax.`` before drawing
    or saving plot:

    """
    # Import matplotlib, set style sheet
    if style_sheet is not None:
        _set_mpl_style_sheet(style_sheet)

    import matplotlib.pyplot as plt
    from matplotlib import dates

    # Set up plot axes and style if needed.
    if ax is None:
        ax = plt.gca()
    if style_kwargs is None:
        style_kwargs = {}
    style_kwargs = dict(style_kwargs)
    style_kwargs.setdefault('linestyle', '-')
    style_kwargs.setdefault('linewidth', 1.5)
    style_kwargs.setdefault('fmt', '-')

    if hasattr(time, 'utcoffset') and use_local_tz:
        tzoffset = time.utcoffset()

of plot, South is always at the bottom, E/W can be right or left
        depending on the ``north_to_east_cw`` option.

        Altitude: 90 degrees (zenith) is at plot origin (center) and 0 degrees
        (horizon) is at plot edge.  This cannot be changed by user.

        Azimuth: 0 degrees is at North (top of plot), 90 degrees at East, etc.
        DANGER: Azimuth labels can be changed by user via the
        ``az_label_offset`` option, but it is not recommended, as to do so
        makes it seem as if N/E/S/W are being decoupled from the definition
        of azimuth (North from az = 0 deg., East from az = 90 deg., etc.).

    """
    # Import matplotlib, set style sheet
    if style_sheet is not None:
        _set_mpl_style_sheet(style_sheet)

    import matplotlib.pyplot as plt

    # Set up axes & plot styles if needed.
    if ax is None:
        ax = plt.gca(projection='polar')
    if style_kwargs is None:
        style_kwargs = {}
    style_kwargs = dict(style_kwargs)
    style_kwargs.setdefault('marker', 'o')

    # Turn scalar Time objects into arrays.
    time = Time(time)
    if time.isscalar:
        time = Time([time])

min_region : float
        If set, defines an interval between ``min_altitude`` and ``min_region``
        that will be shaded. Default is `None`.

    max_region : float
        If set, defines an interval between ``max_altitude`` and ``max_region``
        that will be shaded. Default is `None`.

    Returns
    -------
    ax : `~matplotlib.axes.Axes`
        An ``Axes`` object with added altitude vs. time plot.
    """
    # Import matplotlib, set style sheet
    if style_sheet is not None:
        _set_mpl_style_sheet(style_sheet)

    import matplotlib.pyplot as plt
    from matplotlib import dates

    # Set up plot axes and style if needed.
    if ax is None:
        ax = plt.gca()
    if style_kwargs is None:
        style_kwargs = {}
    style_kwargs = dict(style_kwargs)
    style_kwargs.setdefault('linestyle', '-')
    style_kwargs.setdefault('linewidth', 1.5)
    style_kwargs.setdefault('fmt', '-')

    # Populate time window if needed.
    time = Time(time)

to set plotting styles.

    style_sheet : dict or `None` (optional)
        matplotlib style sheet to use. To see available style sheets in
        astroplan, print *astroplan.plots.available_style_sheets*. Defaults
        to the light theme.

    Returns
    -------
    ax :  `~matplotlib.axes.Axes`
        An ``Axes`` object with added parallactic angle vs. time plot.

    """
    # Import matplotlib, set style sheet
    if style_sheet is not None:
        _set_mpl_style_sheet(style_sheet)

    import matplotlib.pyplot as plt

    from matplotlib import dates

    # Set up plot axes and style if needed.
    if ax is None:
        ax = plt.gca()
    if style_kwargs is None:
        style_kwargs = {}
    style_kwargs = dict(style_kwargs)
    style_kwargs.setdefault('linestyle', '-')
    style_kwargs.setdefault('fmt', '-')

    # Populate time window if needed.
    time = Time(time)