Use of [infix](http://adv-r.had.co.nz/Functions.html#:~:text=Default%20and%20missing%20arguments&text=You%20can%20determine%20if%20an,with%20the%20missing()%20function.&text=Sometimes%20you%20want%20to%20add,lines%20of%20code%20to%20compute.) for d01 in d02 syntax to get a better syntax to specific selection of variables to evaluate the model.
