Number of Entries in an roAssociativeArray

It strikes me as kind of odd that there's no method on the roAssociativeArray object to access the number of entries it has, at least it's no listed in section 10.13 of the BrightScript Reference doc which lists all the methods for this class. Is there method that's missing from the documentation to accomplish this or do I need to an O(n) operation like below to determine the size of an associative array?

-Mark

Function AssocArrayCount(aa as object) as Integer                                                                 
    'Returns the number of entries in an roAssociativeArray                                                       
    i = 0                                                                                                         
    for each k in aa                                                                                              
        i = i + 1                                                                                                 
    end for                                                                                                       
    return i                                                                                                      
End Function