Driver Code
let str = " " ; document . write ( " " + str + " " ) ; let start = isConsecutive ( str ) ; if ( start != - 1 ) document . write ( " " + start + " " ) ; else document . write ( " " ) ; let str1 = " " ; document . write ( " " + str1 + " " ) ; start = isConsecutive ( str1 ) ; if ( start != - 1 ) document . write ( " " + start + " " ) ; else document . write ( " " ) ;