def _start_lt_end(params):
    """Check that 'start' param is < 'end' param
    if both params are found in the provided dict.
    In-place edit of params.

    Parameters
    ----------
    params : dict
        {param_ID:param_value}
    """
    if ('start' in params) & ('end' in params):
        try:
            startVal = float(params['start'])
            endVal = float(params['end'])
        except TypeError:
            return None            
            
        if startVal > endVal:
            params['start'] = endVal
            params['end'] = startVal
        elif startVal == endVal:
            # start-end cannot ==
            if endVal >= 100:
                params['start'] = startVal - 1e-10
            else:
                params['end'] = endVal + 1e-10