module RBS
  def self.logger: () -> Logger

  def self.logger_level: () -> Integer?

  def self.logger_level=: (Integer?) -> Integer?

  def self.logger_output: () -> IO

  def self.logger_output=: (IO) -> IO

  def self.print_warning: () { () -> String } -> void

  self.@logger: Logger?

  self.@logger_output: IO?

  self.@logger_level: Integer?

  self.@warnings: Set[String]
end