class Rufo::Formatter

def trailing_commas(value)

* :never: never put a comma
* :always: always put a comma (default)
* :dynamic: if there's a comma, keep it. If not, don't add it

Whether to place commas at the end of a multi-line list 
def trailing_commas(value)
  case value
  when :dynamic, :always, :never
    @trailing_commas = value
  else
    raise ArgumentError.new("invalid value for trailing_commas: #{value}. Valid values are: :dynamic, :always, :never")
  end
end