def add_subplot(plotfig, subrows=1, subcols=1, subno=1, **kwargs):
    """
    
    Add a new subplot to an existing figure. Matplotlib wrapper.
    This function allows a caller to create a figure and add subplots
    to it without needing to import the matplotlib library separately.

    :Parameters:
    
    plotfig: matplotlib figure object
        Figure on which to add the plot.
    subrows: int, optional
        The total number of subplot rows within the figure
    subcols: int, optional
        The total number of subplot columns within the figure
    subno: int, optional
        The running number for this particular subplot.
    \*\*kwargs:
        All other keyword arguments will be passed to matplotlib.add_subplot 
        
    :Returns:
       
    plotaxis: matplotlib axis object
        The axis object just created.
        
    """
    if plotfig is not None:
        return plotfig.add_subplot(subrows, subcols, subno, **kwargs)
    else:
#         logger.warning("matplotlib figure not available")
        return None