model_list <- add_expr(
  list(),
  substitute(
    expr = {
      TRUE
      "A VERY VERY LONG STRINGA VERY VERY LONG STRINA VERY VERY LONG STRINA VERY VERY LONG STRINA VERY VERY LONG STRINA VERY VERY LONG STRINGGGGG"
    },
    env = list(
      data_model_fit = as.name(data_model_fit),
      aval_var = aval_var,
      split_covariates = split_covariates,
      id_var = id_var,
      arm_var = arm_var,
      visit_var = visit_var,
      cor_struct = cor_struct
    )
  )
)