method MemoryTable.prototype.onBeforeChangeimport { MemoryTable } from "https://dotland.deno.dev/x/pg_mem@2.6.3/table.ts"; onBeforeChange(columns: "all" | (string | _Column)[], check: ChangeHandler<T>): ISubscriptionParameterscolumns: "all" | (string | _Column)[]check: ChangeHandler<T>ReturnsISubscription