class ActionView::Helpers::DateTimeSelector

def separator(type)

Returns the separator for a given datetime component. 
def separator(type)
  return "" if @options[:use_hidden]
  case type
  when :year, :month, :day
    @options[:"discard_#{type}"] ? "" : @options[:date_separator]
  when :hour
    (@options[:discard_year] && @options[:discard_day]) ? "" : @options[:datetime_separator]
  when :minute, :second
    @options[:"discard_#{type}"] ? "" : @options[:time_separator]
  end
end