F_est                   Estimate the Conditional CDF of the Event Time
                        given Covariates
G_est                   Estimate the Conditional CDF for the Left
                        Truncation Time given Covariates
simu                    A Simulated Data Set under Left Truncation but
                        No Right Censoring
simu_c1                 A Simulated Data Set under Left Truncation and
                        Right Censoring where Censoring can be before
                        Truncation
simu_c2                 A Simulated Data Set under Left Truncation and
                        Right Censoring where Censoring is always after
                        Truncation
truncAIPW               Doubly Robust Estimation under
                        Covariate-induced Dependent Left Truncation and
                        No Censoring
truncAIPW_cen1          Doubly Robust Estimation under
                        Covariate-induced Dependent Left Truncation and
                        Noninformative Right Censoring where Censoring
                        can be before Left Truncation
truncAIPW_cen2          Doubly Robust Estimation under
                        Covariate-induced Dependent Left Truncation and
                        Noninformative Right Censoring where Censoring
                        is always after Left Truncation
