code: function interpolateRequest(params, bindings) {
  
    params.body = interpolate(params.body, bindings, { json: true })
    params.path = interpolate(params.path, bindings)
    for (var key in params.headers) {
      params.headers[key] = interpolate(params.headers[key], bindings)
    }
    return params
  }
docs: Internal: interpolate the values from `bindings` into the `params` struct