class RuboCop::Cop::Performance::RedundantStringChars

def build_good_method(method, args)
  case method
  when :slice
    "[#{build_call_args(args)}].chars"
  when :[], :first
    build_good_method_for_brackets_or_first_method(method, args)
  when :last
    '[-1]'
  when :take
    "[0...#{args.first.source}].chars"
  else
    ".#{method}"
  end
end