class Plumb::Not

def [](step)
  self.class.new(step)
end

def _inspect
#{@step.inspect}))

def call(result)
  result = @step.call(result)
  result.valid? ? result.invalid(errors: @errors) : result.valid
end

def initialize(step = nil, errors: nil)
  @step = Composable.wrap(step)
  @errors = errors || "must not be #{step.inspect}"
  @children = [step].freeze
  freeze
end