code: def _deriv_growth(z, **cosmo):
      
  
      inv_h = (cosmo['omega_M_0']*(1 + z)**3 + cosmo['omega_lambda_0'])**(-0.5)
      fz = (1 + z) * inv_h**3
  
      deriv_g = growthfactor(z, norm=True, **cosmo)*(inv_h**2) *\
          1.5 * cosmo['omega_M_0'] * (1 + z)**2 -\
          fz * growthfactor(z, norm=True, **cosmo)/_int_growth(z, **cosmo)
  
      return(deriv_g)
docs: Returns derivative of the linear growth factor at z
          for a given cosmology **cosmo