<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _sigma_inel(self, Ep):
 """ Inelastic cross-section for p-p interaction. KAB06 Eq. 73, 79 Note: Quantities are not used in this function Parameters Ep : float Eprot [TeV] Returns ------- sigma_inel : float Inelastic cross-section for p-p interaction [1/cm2]. """

        L = np.log(Ep)
        sigma = 34.3 + 1.88 * L + 0.25 * L ** 2
        if Ep <= 0.1:
            Eth = 1.22e-3
            sigma *= (1 - (Eth / Ep) ** 4) ** 2 * heaviside(Ep - Eth)
        return sigma * 1e-27