Get active groups

[not-so-smart]

GroupManager#fetch(): Promise<Collection<string, Group>> GroupManager#fetch(id: string): Promise<Group> GroupManager#fetch(ids: string[]): Promise<Collection<string, Group | null>>

Fetches groups. If called with no parameters, fetches all groups. If a single group ID is specified, fetches only that group. If an array of group IDs is specified, fetches those groups and returns a Collection of groups fetched.

Usage:

client.groups.fetch()
client.groups.fetch('123456789')
client.groups.fetch(['123456789', '987654321'])