class ActiveSupport::Multibyte::Chars

def slice!(*args)

string # => 'me'
string.mb_chars.slice!(0..3) # => #
string # => 'Welome'
string.mb_chars.slice!(3) # => #
string = 'Welcome'

modified if the range given is out of bounds
Chars, or +nil+ if the string was not modified. The string will not be
Works like String#slice!, but returns an instance of 
def slice!(*args)
  string_sliced = @wrapped_string.slice!(*args)
  if string_sliced
    chars(string_sliced)
  end
end