anchor.diff:  
   === Quick solution - Not scalable
   Let's say that you want to monitor a bunch of samples in BioSamples and
  -anytime a sample is updated you want to retrieve the new content into your system.
  +whenever a sample is updated you want to retrieve the new content into your system.
   
   One way of doing this is to have a list of accession and at a scheduled interval
   retrieve the samples from BioSamples and check if the update date on the sample
  
positive.code: content-length: 1488
  ```
  
  === 2. Submit a new GET request
  
  Let's submit a new request with the `If-None-Match` header and the ETAG
  
  
negative.code: x-frame-options: DENY
  ```
  
  === 3. Submit a GET request with an older ETAG
  
  Let's pretended that your locally stored ETAG is different, like "07b2dc735675d4f54f0dc3df82c34daa1".
  
  If you use that in the conditional request, you will get a 200 - OK response with the original sample content
  
  ```
  curl -H "Accept: application/json" -H 'If-None-Match: "07b2dc735675d4f54f0dc3df82c34daa1"' -i https://www.ebi.ac.uk/biosamples/samples/SAMEA2614688
  ```
  
  and here the response headers
  ```
  HTTP/2 200
  cache-control: max-age=60, public
  content-type: application/json;charset=UTF-8
  strict-transport-security: max-age=0
  date: Thu, 18 Oct 2018 15:40:54 GMT
  x-application-context: application:8081
  x-xss-protection: 1; mode=block
  x-content-type-options: nosniff
  etag: "06b2bf5fb11041e36ad4c29a77ff3be55"
  x-frame-options: DENY
  content-length: 1488
  ```
  
  == Template
  
  Here the template for the curl request for you to try to use the ETAG functionality
  