(f)ind (b)ars e(x)tended: recursive
fbx(term, debug = FALSE, specials = character(0), default.special = "us")
a formula or piece of a formula
(logical) debug?
list of special terms
character: special to use for parenthesized terms - i.e. random effects terms with unspecified structure 1. atom (not a call or an expression): NULL 2. special, i.e. foo(...) where "foo" is in specials: return term 3. parenthesized term: if the head of the head is | (i.e. it is of the form (xx|gg), then convert it to the default special type; we won't allow pathological cases like ((xx|gg)) ... [can we detect them?]