class T::Enum

def initialize(serialized_val=nil)
  raise 'T::Enum is abstract' if self.class == T::Enum
  if !self.class.started_initializing?
    raise "Must instantiate all enum values of #{self.class} inside 'enums do'."
  end
  if self.class.fully_initialized?
    raise "Cannot instantiate a new enum value of #{self.class} after it has been initialized."
  end
  serialized_val = serialized_val.frozen? ? serialized_val : serialized_val.dup.freeze
  @serialized_val = T.let(serialized_val, T.nilable(SerializedVal))
  @const_name = T.let(nil, T.nilable(Symbol))
  self.class._register_instance(self)
end