src/http.js
function setup_headers(headers) {
    keys(headers).forEach(function(key) {
      client.setRequestHeader(key, headers[key]) })}
function setup_headers(headers) {
    keys(headers).forEach(function(key) {
      client.setRequestHeader(key, headers[key]) })}
Setups the headers for the HTTP request setup-headers :: { String -> String | [String] } -> Undefined