ss='va'>tickers</span>,
                        start <span class='op'>=</span> <span class='fu'><a href='https://rdrr.io/pkg/zoo/man/yearmon.html'>as.Date</a></span><span class='op'>(</span><span class='st'>"2019-04-01"</span><span class='op'>)</span>,
                        end <span class='op'>=</span> <span class='fu'><a href='https://rdrr.io/pkg/zoo/man/yearmon.html'>as.Date</a></span><span class='op'>(</span><span class='st'>"2020-04-01"</span><span class='op'>)</span>,
                        quote 