esti_mean_treat         Estimate treatment effect and the corresponding
                        variance estimation on the treatment arm using
                        different covariate adjustment methods.
fit.adj2.adj2c.Random   Covariate-Adjusted Treatment Effect Estimation
                        under the Randomization-based Framework
fit.adj2.adj2c.Super    Covariate-Adjusted Treatment Effect Estimation
                        under the Super-Population Framework
get_oracle_bias_var_adj2c
                        Estimate the oracle bias, the exact variance
                        and approximated variance of the debiased
                        estimator tau_adj2c inspired by HOIF (Zhao et
                        al.(2024)).
get_oracle_bias_var_adj_2_3
                        Estimate the oracle bias, the exact variance
                        and approximated variance of the debiased
                        estimator and the bias-free estimator motivated
                        by HOIF (Zhao et al.(2024)).
get_oracle_bias_var_adj_db
                        Estimate the oracle bias, the oracle variance
                        of the unadjusted estimator, the adjusted
                        estimator by Lei’s (2020) and the debiased
                        estimator tau_db by Lu et al.(2023).
