def printVLines(ax, xCoords, width=0.05, color='gray', alpha=0.75, lStyle='--'
    ):
    """Adds vertical lines to the plot in the list of x-coordinates passed.
        Created as an auxiliary function to mark days at which events happen
        (threshold crossings).

    Parameters
    ----------
    ax : Matplotlib axes
        Can be obtained from a figure with: fig.get_axes()[0]
    xCoords : list
        A list containing the xCoordinates of all the lines to print.
    width : float
        Line width (weight).
    color : color
        Color id for the lines to be drawn.
    alpha : float
        Alpha to apply to the lines.
    lStyle : Matplotlib line-style
        Matplotlib dash-line style:
        https://matplotlib.org/gallery/lines_bars_and_markers/line_styles_reference.html

    Returns
    -------
    ax
        Returns the changed ax with the modification performed.

    """
    for vLine in xCoords:
        ax.axvline(x=vLine, linewidth=width, linestyle=lStyle, color=color,
            alpha=alpha)
    return ax
