docs: def vinet_p(v, v0, k0, k0p):
      """
      calculate pressure from vinet equation
  
      :param v: unit-cell volume in A^3
      :param v0: unit-cell volume in A^3 at 1 bar
      :param k0: bulk modulus at reference conditions
      :param k0p: pressure derivative of bulk modulus at reference conditions
      :return: pressure in GPa
      """
      # unumpy.exp works for both numpy and unumpy
      # so I set uncertainty default.
      # if unumpy.exp is used for lmfit, it generates an error
      return cal_p_vinet(v, [v0, k0, k0p],
                         uncertainties=isuncertainties([v, v0, k0, k0p]))