atom

# File lib/net/imap.rb, line 3296
      def atom
        result = String.new
        while true
          token = lookahead
          if atom_token?(token)
            result.concat(token.value)
            shift_token
          else
            if result.empty?
              parse_error("unexpected token %s", token.symbol)
            else
              return result
            end
          end
        end
      end