@kamino-finance/klend-sdk/src/utils/map.ts

Typescript SDK for interacting with the Kamino Lending (klend) protocol

export function setOrAppend<K, V>(map: Map<K, V[]>, key: K, value: V): void {
  const existing = map.get(key);
  if (existing) {
    existing.push(value);
  } else {
    map.set(key, [value]);
  }
}