s = "hello"
s[2..3] # "ll": characters 2 and 3
s[-3..-1] # "llo": negative indexes work, too
s[0..0] # "h": this Range includes one character index
s[0...0] # "": this Range is empty
s[2..1] # "": this Range is also empty
s[7..10] # nil: this Range is outside the string bounds
s[-2..-1] = "p!" # Replacement: s becomes "help!"
s[0...0] = "Please " # Insertion: s becomes "Please help!"
s[6..10] = "" # Deletion: s becomes "Please!"