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: source.rb
    path of file: ./repos/babushka/lib/babushka
    
    the code of the file until where you have to start completion: module Babushka
  class SourceError < StandardError
  end
  class SourceLoadError < LoadError
  end
  class Source
    include LogHelpers
    extend LogHelpers
    extend ShellHelpers
    include PathHelpers
    extend PathHelpers

    attr_reader :path, :name, :uri, :deps, :templates

    def self.present
      source_prefix.glob('*').map {|path|
        Source.for_path(path.p)
      }
    end

    def self.for_path path
      source = Source.new(path)
      @sources ||= {}
      @sources[source.name] ||= source
    end

    def self.for_remote name
      Source.new(nil, name, default_remote_for(name))
    end

    def self.default_remote_for name
      if name == 'common'
        # This is a special case.
        "https://github.com/benhoskings/common-babushka-deps.git"
      else
        "https://github.com/#{name}/babushka-deps.git"
      end
    end

    def initialize path, name = nil, uri = nil
      raise ArgumentError, "Sources with nil paths require a name (as the second argument)." if path.nil? && name.nil?
      raise
    
    def initialize path, name = nil, uri = nil
      raise ArgumentError, "Sources with nil paths require a name (as the second argument)." if path.nil? && name.nil?
      raise ArgumentError, "The source URI can only be supplied if the source doesn't exist already." if !uri.nil? && !path.nil? && path.p.exists?
      init
      @path = path.p unless path.nil?
      @name = name
      @uri = uri
    end

    def path
      @path ||= (Source.source_prefix / name).p
    end

    def name
      @name ||= path.basename.to_s
    end

    def uri
      @uri ||= detect_uri
    end

    def present?
      path.exists?
    end

    def type
      uri.nil? ? :local : :remote
    end

    def implicit?
      type == :implicit
    end

    def local?
      type == :local
    end

    def remote?
      type == :remote
    end

    def repo
      @repo ||= Babushka::GitRepo.new(path)
    end

    def repo?
      repo.exists? && (repo.root == path)
    end

    def updated_at
      Time.now - File.mtime(path)
    end

    def description_pieces
      [
        name,
        uri.to_s,
        type,
        ("#{updated_at.round.xsecs} ago" if remote?)
      ]
    end

    def == other
      [:name, :uri, :type].all? {|method_name| other.respond_to? method_name } &&
      name == other.name &&
      uri == other.uri &&
      type == other.type
    end

    def find dep_spec
      load!
      deps.for(dep_spec)
    end

    def find_template template_spec
      load!
      templates.for(template_spec)
    end

    def add!
      if !remote?
        log "Nothing to add for #{name}."
      else
        raise_unless_addable!
        update!
      end
    end