def METHOD_NAME(ts, coors, mode=None):
    """
    Pressure traction.
    Parameters
    ----------
    ts : TimeStepper
        Time stepping info.
    coors : array_like
        The physical domain coordinates where the parameters shound be defined.
    mode : 'qp' or 'special'
        Call mode.
    """
    if mode != 'qp': return
    tt = ts.nt * 2.0 * nm.pi
    dim = coors.shape[1]
    val = 0.05 * nm.sin(tt) * nm.eye(dim, dtype=nm.float64)
    val[1,0] = val[0,1] = 0.5 * val[0,0]
    shape = (coors.shape[0], 1, 1)
    out = {
        'pressure' : nm.tile(val, shape),
    }
    return out