Yes: "10", from = '10', to = ''
Yes: "10,20", from = '10', to = '20'
Yes: ".,20", from = '.', to = '20'
Yes: "20,$", from = '20', to = '$'
Yes: "/abc/,.", from = '/abc/', to = '.'
Yes: ".-5,.+10", from = '.-5', to = '.+10'
Yes: "/begin/,/end/", from = '/begin/', to = '/end/'
Yes: "/testing/", from = '/testing/', to = ''
Yes: ".+10", from = '.+10', to = ''
Yes: ".,.", from = '.', to = '.'
Yes: ".", from = '.', to = ''
Yes: "$", from = '$', to = ''
No: "+10"
No: ".."
No: "$,,."
No: "10,"
No: "begin/,end/"
No: "end/"
No: ",20"
No: ",,,"
No: "..+10"