Just because I needed something to occupy my time, here's something similar in bash shell script for linux...

#!/bin/bash
# Take API from first command line argument.  Use steemit if none given.
STEEMAPI="${1:-https://api.steemit.com}"

show_time_block_witness()
{
   NOW=$(date)
   curl -s --data '{"jsonrpc":"2.0", "method":"condenser_api.get_dynamic_global_properties", "params":[], "id":1}' ${STEEMAPI} \
      2>/dev/null \
      | jq -c -S '.result | {head_block_number, current_witness}' \
      | tr '[,:"{}]' ' ' \
      | ( read LBL1 BLOCK LBL2 WITNESS ; echo ${NOW}: ${BLOCK} ${WITNESS} )
}

SLEEPTIME=3
MAX=20 # Approximately 1 minute
for (( i=1; i <= ${MAX} ; i++ ))
do
   sleep ${SLEEPTIME} &
   show_time_block_witness
   wait
done