get (database, defaultSupplier) {
    if (this._tables.has(database)) {
      return this._tables.get(database)
    }
    return typeof defaultSupplier === 'function'
      ? defaultSupplier()
      : defaultSupplier
  }
Retrieves a routing table from a given database name

@param {string|impersonatedUser} impersonatedUser The impersonated User
@param {string} database The database name
@param {function()|RoutingTable} defaultSupplier The routing table supplier, if it's not a function or not exists, it will return itself as default value
@returns {RoutingTable} The routing table for the respective database