+declare -g ots_delay; ots_delay=1 # minimum time in seconds between ots operations
+declare -ag calendars;
+calendars+=("https://finney.calendar.eternitywall.com");
+calendars+=("https://btc.calendar.catallaxy.com");
+calendars+=("https://alice.btc.calendar.opentimestamps.org");
+calendars+=("https://bob.btc.calendar.opentimestamps.org");