class Polars::LazyFrame

def collect(
  engine: "auto",
  background: false,
  optimizations: DEFAULT_QUERY_OPT_FLAGS
)
  engine = _select_engine(engine)
  if engine == "streaming"
    Utils.issue_unstable_warning("streaming mode is considered unstable.")
  end
  ldf = _ldf.with_optimizations(optimizations._rboptflags)
  if background
    Utils.issue_unstable_warning("background mode is considered unstable.")
    return InProcessQuery.new(ldf.collect_concurrently)
  end
  Utils.wrap_df(ldf.collect(engine))
end