module BCDD::Contract::Assertions
  def assert!: (untyped, String) { (untyped) -> bool } -> untyped
  def refute!: (untyped, String) { (untyped) -> bool } -> untyped

  def assert: (untyped, String) { (untyped) -> bool } -> untyped
  def refute: (untyped, String) { (untyped) -> bool } -> untyped
end