Synopsis:
   $getarrays(<pattern>)

Technical:
   This function returns a space-seperated list of the names of the existing
   arrays created by $setitem() that match the given pattern.
   If the <pattern> argument is omitted all current arrays are returned.

Practical:
   This function is used to find all current arrays. This might be useful
   for modifying data in multiple arrays, when it is not known precisely
   which ones exist at the moment in question.

Returns:
   list of array names, or nothing if none are set

See Also:
   Arrays(7); setitem(6)