def attach(ary, options = {})
      attachments = ary.is_a?(Array) ? ary : [ ary ] #force first arg to array
      post({ attachments: attachments }.merge(options))
    end
def attach(ary, options = {})
      attachments = ary.is_a?(Array) ? ary : [ ary ] #force first arg to array
      post({ attachments: attachments }.merge(options))
    end
simple wrapper on post to send attachment(s)