Sends every request at once, at most parallel_downloads at a
time, and waits for all of them, so 44 indices take about as long as the
slowest few instead of the sum of all of them.
Value
A list with an element per address, in the same order: a list with
the status_code and the raw content of the answer, or with the
error message when the request could not be made.
Examples
if (FALSE) { # \dontrun{
golemstockindices:::fetch_all(c("https://example.com", "https://example.org"))
} # }