const str = "abcdefg"
var n = 2
var m = 3

println (str[n:n+m-1])    // pos 2 length 3
println (str[n:])           // pos 2 to end
println (str >> 1)      // remove last character
var p = find (str, 'c')
println (str[p:p+m-1])    // from pos of p length 3

var s = find (str, "bc")
println (str[s, s+m-1])    // pos of bc length 3