anchor.diff:  using the optional argument `headers`:
   *)
   
  -Http.Request
  +Http.RequestString
     ( "http://httpbin.org/post", 
       headers = ["content-type", "application/json"],
       body = ReqBody.Text """ {"test": 42} """)
   
   (**
   You can also send binary data in the HTTP POST request's body. Just change the header appropriately 
  -and use the `Body.Binary` constructor in your request.
  +and use the `ReqBody.Binary` constructor in your request.
   *)
   
   let myBinaryData = System.Text.Encoding.UTF8.GetBytes "Hello!"
   
  -Http.Request
  +Http.RequestString
     ( "http://httpbin.org/post", 
       headers = ["content-type", "application/octet-stream"],
       body = ReqBody.Binary myBinaryData )
  +
  +(**
  +## Sending a client certificate
  +
  +If you want to add a client certificate to your requests, then you can use the 
  +optional parameter `certificate` and pass the `X509ClientCertificate` value as
  +an argument. To do that, you need to open the `X509Certificates` namespace from 
  +`System.Security.Cryptography`. Assuming the certificate is stored in `myCertificate.pfx`,
  +you can write:
  +*)
  +
  +
  +open System.Security.Cryptography.X509Certificates
  +
  +let clientCert = new X509Certificate2 (".\myCertificate.pfx", "password")
  +
  +Http.RequestString("http://yourprotectedresouce.com/data",
  +             certificate = clientCert)
  +
   
   (**
   ## Maintaing cookies across requests
  
positive.code:     printfn "Got text content: %s" text
  | ResBody.Binary bytes -> 
      printfn "Got %d bytes of binary content" bytes.Length
  
  (**
  ## Sending a client certificate
  
  If you want to add a client certificate to your requests, then you can use the 
  optional parameter `certificate` and pass the `X509ClientCertificate` value as
  an argument. To do that, you need to open the `X509Certificates` namespace from 
  `System.Security.Cryptography`. Assuming the certificate is stored in `myCertificate.pfx`,
  you can write:
  *)
  
  open System.Security.Cryptography.X509Certificates
  
  // Load the certificate from local file
  let clientCert = 
    new X509Certificate2(".\myCertificate.pfx", "password")
  
  // Send the request with certificate
  Http.Request
    ( "http://yourprotectedresouce.com/data",
      certificate = clientCert)
  
negative.code: specifies the GET method, but it will be set automatically for you if you omit it:
  *)
  
  Http.RequestString("http://httpbin.org/get", query=["test", "foo"], meth="GET")
  
  (** 
  Additional headers are specified similarly - using an optional parameter `headers`.
  