def ms2knot(ws_ms):
    """
    Convert unit of wind speed from meter per seconds to knots.
    
    Examples
    ---------
    >>> ws_knot = kkpy.util.ms2knot(ws_ms)
    
    Parameters
    ----------
    ws_ms : array_like
        Array containing wind speed in **m/s**.
        
    Returns
    ---------
    ws_knot : ndarray
        Return wind speed in **knots**.
    """
    
    ws_knot = ws_ms * 1. / 0.5144444
    
    return ws_knot