Function pattern

pattern(
    type: PatternType,
    gsv: number | boolean,
    loc?: LocationTrace,
    children?: readonly Thing<string | ThingType>[],
    start?: string,
    end?: string,
    join?: string,
): Thing<pattern>
Parameters
- type: PatternType
- gsv: number | boolean
- loc: LocationTrace = UNKNOWN_LOCATION
- children: readonly Thing<string | ThingType>[] = []
- start: string = ""
- end: string = ""
- join: string = ""
Returns Thing<pattern>