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: scalar_scanner.rb
    path of file: ./repos/powerstation/powerstation/lib/compiled-jruby/lib/ruby/stdlib/psych
    
    the code of the file until where you have to start completion: require 'strscan'

modul
    
    def tokenize string
      return nil if string.empty?
      return string if @string_cache.key?(string)
      return @symbol_cache[string] if @symbol_cache.key?(string)

      case string
      # Check for a String type, being careful not to get caught by hash keys, hex values, and
      # special floats (e.g., -.inf).
      when /^[^\d\.:-]?[A-Za-z_\s!@#\$%\^&\*\(\)\{\}\<\>\|\/\\~;=]+/, /\n/
        if string.length > 5
          @string_cache[string] = true
          return string
        end