def rs_cosh(p, x, prec):
    """
    Hyperbolic cosine of a series

    Return the series expansion of the cosh of ``p``, about 0.

    Examples
    ========

    >>> from sympy.polys.domains import QQ
    >>> from sympy.polys.rings import ring
    >>> from sympy.polys.ring_series import rs_cosh
    >>> R, x, y = ring('x, y', QQ)
    >>> rs_cosh(x + x*y, x, 4)
    1/2*x**2*y**2 + x**2*y + 1/2*x**2 + 1

    See Also
    ========

    cosh
    """
    if rs_is_puiseux(p, x):
        return rs_puiseux(rs_cosh, p, x, prec)
    t = rs_exp(p, x, prec)
    t1 = rs_series_inversion(t, x, prec)
    return 2/(t + t1)
dataset/ETHPy150Open sympy/sympy/sympy/polys/ring_series.py/rs_cosh/swapped operands of `/`