def get(name)
      name = normalize_header name.to_s
      @pile.select { |k, _| k == name }.map { |_, v| v }
    end
def get(name)
      name = normalize_header name.to_s
      @pile.select { |k, _| k == name }.map { |_, v| v }
    end
Returns list of header values if any.

 @return [Array<String>]