curl --request POST \
  --url https://api.example.com/EXPERIMENTAL_changes_in_block \
  --header 'Content-Type: application/json' \
  --data '
{
  "method": "EXPERIMENTAL_changes_in_block",
  "params": {
    "block_id": 1
  },
  "id": "dontcare",
  "jsonrpc": "2.0"
}
'

const options = {
  method: 'POST',
  headers: {'Content-Type': 'application/json'},
  body: JSON.stringify({
    method: 'EXPERIMENTAL_changes_in_block',
    params: {block_id: 1},
    id: 'dontcare',
    jsonrpc: '2.0'
  })
};

fetch('https://api.example.com/EXPERIMENTAL_changes_in_block', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

import requests

url = "https://api.example.com/EXPERIMENTAL_changes_in_block"

payload = {
    "method": "EXPERIMENTAL_changes_in_block",
    "params": { "block_id": 1 },
    "id": "dontcare",
    "jsonrpc": "2.0"
}
headers = {"Content-Type": "application/json"}

response = requests.post(url, json=payload, headers=headers)

print(response.text)

{
  "result": {
    "block_hash": "<string>",
    "changes": [
      {
        "account_id": "<string>",
        "type": "account_touched"
      }
    ]
  },
  "id": "<string>",
  "jsonrpc": "<string>"
}