Internal helper to eagerly build assignment conditions for potential outcomes.
expand_conditions(formula, conditions = c(0, 1),
assignment_variables = "Z", data, level = NULL, label = NULL)the conditions
the name of assignment variables, if conditions is not already named.
a data.frame of potential outcome conditions
If conditions is a data.frame, it is returned unchanged
Otherwise, if conditions is a list, it is passed to expand.grid for expansion to a data.frame
Otherwise, if condition is something else, box it in a list with assignment_variables for names, and pass that to expand.grid.