You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: singular_association.rb
    path of file: ./repos/associationist/lib/associationist/builder
    
    the code of the file until where you have to start completion: module Associationist
  module Builder
    class SingularAssociation < ::ActiveRecord::Associations::Builder::SingularAssociation
      def self.valid_options(options)
        super + [:associationist]
      end

      def
    
      def self.create_reflection(model, name, scope, options, extension = nil)
        raise ArgumentError, "association names must be a Symbol" unless name.kind_of?(Symbol)

        validate_options(options)
        case
        when ActiveRecord.version >= Gem::Version.new('6.0.0')
          scope = build_scope(scope)
        else
          scope = build_scope(scope, extension)
        end