output.txt

$ ruby x.rb 
Address: 1FBVmnKtjgA676Xbatqx42dcGzaaPV4BU4 contains 4 transactions.
Address: 17j92xE73rEyexJSB4gwavd2YkpTKZWfAv contains 7 transactions.

x.rb

require 'net/http'
require 'json'
require 'net/https'
require 'uri'

addrs = [
  '1FBVmnKtjgA676Xbatqx42dcGzaaPV4BU4',
  '17j92xE73rEyexJSB4gwavd2YkpTKZWfAv'
]

url = URI.parse(
  "http://chain-api-staging.herokuapp.com"+
  "/v1/bitcoin/addresses/#{addrs.join(',')}/transactions"
)

http = Net::HTTP.new(url.host, url.port)
req = Net::HTTP::Get.new(url.path)
req.basic_auth('GUEST-TOKEN', '')
res = http.request(req)
txns = JSON.parse(res.body)

addrs.each_with_index do |addr, idx|
  puts("Address: #{addr} contains #{txns[idx].length} transactions.")
end