A function to combine nlme-style fixed and random effects formulas into lme4 style formulas.
combine_formula_lists(fixed, random, warn = TRUE)
a fixed effects formula or list of such formulas
a random effects formula (only RHS) or list of such formulas
logical; should the warning(s) be printed
Internal function.
Lists of formulas can be named or unnamed.
Uses combine_formulas()
.