import re
line='"start_nm":"BOSTON","dest_nm":"NEW YorK"'
match1 = re.search('start_nm\":\"([^"]*)', line)
if match1:
print(match1.group(1))
aW1wb3J0IHJlCmxpbmU9JyJzdGFydF9ubSI6IkJPU1RPTiIsImRlc3Rfbm0iOiJORVcgWW9ySyInCm1hdGNoMSA9IHJlLnNlYXJjaCgnc3RhcnRfbm1cIjpcIihbXiJdKiknLCBsaW5lKQppZiBtYXRjaDE6CiAgICBwcmludChtYXRjaDEuZ3JvdXAoMSkp