A thin wrapper around base::Position() to search through a list of language
objects, as produced by flatten_call() or flatten_expr(), for the
presence of a specific symbol.
position_symbol(x, sym, ...)The position of the symbol if found, or the nomatch value
otherwise.
(list of language)
a list of language objects in which to
search for a specific symbol.
(name or symbol or character)
a symbol to search for in
x.
Additional arguments passed to Position().