if.rb

class NilClass
  def if
    self
  end

  def else
    yield self
  end
end

class FalseClass
  def if
    self
  end

  def else
    yield self
  end
end

class Object
  def if
    yield self
  end

  def else
    self
  end
end

class User
  def self.find_by(id:)
    if id == 1
      self.new
    else
      nil
    end
  end
end

User.find_by(id: 1).if do |user|
  p user # => print user
end

User.find_by(id: 2).if do |user|
  p user # => not print
end.else do |user|
  p user # => print flase
end

&.tap