const inputBody = '{
  "title": "Products"
}';
const headers = {
  'Content-Type':'application/json',
  'Accept':'application/json'
};
 
fetch('https://{instance}.paligoapp.com/api/v2/variablesets/{id}/',
{
  method: 'PUT',
  body: inputBody,
  headers: headers
})
.then(function(res) {
    return res.json();
}).then(function(body) {
    console.log(body);
});