make_plpr_data          Generates data from a partially linear panel
                        regression (PLPR) model
xtdml                   Abstract class xtdml
xtdml_data              Set up for data for panel data approaches and
                        up two cluster variables
xtdml_data_from_data_frame
                        Wrapper for Double machine learning
                        data-backend initialization from data.frame.
xtdml_plr               Routine to estimate partially linear panel
                        regression models with fixed effects within
                        double machine learning.
