How to extract http-response header?

I've done similar work using the R data connection and httr library.

A sample of my code:

let
    bodyString = "'{""user_name"":"""&Text.From(UserName)&""",""password"":"""&Text.From(Password)&"""}'",
    Source = R.Execute("library(httr)#(lf)library(jsonlite)#(lf)getToken <- POST(""https://endpoint.com/api/v1/login"", add_headers(""Content-Type""=""application/json""), body = "&bodyString&")#(lf)tokenIs <- cookies(getToken)#(lf)getData <- GET(""https://endpoint.com/api/v1/sr?type=request&insert_time=1483257600000,0"", add_headers(""Content-Type""=""application/json""), set_cookies(""name""=tokenIs$name,""value""=tokenIs$value))#(lf)result <- data.frame(content(getData, ""text""))"),
    result1 = Table.ToRecords(Source{[Name="result"]}[Value]),
    #"Converted to Table" = Table.FromList(result1, Splitter.SplitByNothing(), null, null, ExtraValues.Error),
    Column1 = #"Converted to Table"{0}[Column1],
    stuff = Json.Document(Column1[#"content.getData...text.."]),
    #"Converted to Table1" = Table.FromList(stuff, Splitter.SplitByNothing(), null, null, ExtraValues.Error),
    #"Expanded Column1" = Table.ExpandRecordColumn.....

how did you manage to solve this? I am trying to obtain the cookies from a query to the server, cookies that will later serve me to make a request to the login