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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def lambda_tilde(mass1, mass2, lambda1, lambda2):
 """ The effective lambda parameter The mass-weighted dominant effective lambda parameter defined in https://journals.aps.org/prd/pdf/10.1103/PhysRevD.91.043002 """

    m1, m2, lambda1, lambda2, input_is_array = ensurearray(
        mass1, mass2, lambda1, lambda2)
    lsum = lambda1 + lambda2
    ldiff, _ = ensurearray(lambda1 - lambda2)
    mask = m1 < m2
    ldiff[mask] = -ldiff[mask]
    eta = eta_from_mass1_mass2(m1, m2)
    p1 = (lsum) * (1 + 7. * eta - 31 * eta ** 2.0)
    p2 = (1 - 4 * eta)**0.5 * (1 + 9 * eta - 11 * eta ** 2.0) * (ldiff)
    return formatreturn(8.0 / 13.0 * (p1 + p2), input_is_array)