         const toSend = inputGenerator(),
                client = new XMLHttpRequest()
          client.open("POST", "resources/inspect-headers.py?filter_name=Content-Type", false)
          for(header in headersToSend) {
            if (headersToSend.hasOwnProperty(header)) {
              client.setRequestHeader(header, headersToSend[header]);
            }
          }
          client.send(toSend)

          const actual = client.responseText
          if (expectedType === undefined || expectedType === 