[GNC] experience using Alpha Vantage

[John Layman]

I've recently been using Alpha Vantage for quotes anticipating the end of
the line for Yahoo as a Finance::Quote source.  The throttling doesn't slow
things to the point that it is a problem for me, but the results I am
getting are spotty.  While I sometimes get notification that quotes for
certain ticker symbols were not fetched, the reality is that the reported
errors are not comprehensive.  Going to the trouble to actually check
downloaded prices, I find that a number of tickers that were not reported
also failed to download.  And it seems entirely random.  However, I do note
that the missing prices seem always to be FUNDS, never securities or ETFs.
That would suggest that the problem lies with Alpha Vantage, but even if so,
Finance::Quote is failing to catch the "miss".