code: def DRAGONS(flat=False, extras=True):
      
      omega_c_0 = 0.2292
      omega_b_0 = 0.0458
      cosmo = {'omega_b_0': omega_b_0,
               'omega_M_0': omega_b_0 + omega_c_0,
               'omega_lambda_0': 0.725,
               'h': 0.702,
               'n': 0.963,
               'sigma_8': 0.816,
               'tau': 0.088,
               'z_reion': 10.6,
               't_0': 13.76,
               }
      if flat:
          cosmo['omega_lambda_0'] = 1 - cosmo['omega_M_0']
          cosmo['omega_k_0'] = 0.0
      if extras:
          add_extras(cosmo)
      return cosmo
docs: DRAGONS cosmology assumes WMAP7 + BAO + H_0 mean from
      Komatsu et al. (2011) ApJS 192 18K (arxiv:1001.4538v1)
  
      Parameters
      ----------
  
      flat: boolean
  
        If True, sets omega_lambda_0 = 1 - omega_M_0 to ensure omega_k_0
        = 0 exactly. Also sets omega_k_0 = 0 explicitly.
  
      extras: boolean
  
        If True, sets neutrino number N_nu = 0, neutrino density
        omega_n_0 = 0.0, Helium mass fraction Y_He = 0.24.