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: label_set_validator.rb
    path of file: ./repos/client_ruby/lib/prometheus/client
    
    the code of the file until where you have to start completion: # encoding: UTF-8

module Prometheus
  module Client
    # LabelSetValidator ensures that all used label sets comply with the
    # P
    
      def validate_labelset!(labelset)
        begin
          return labelset if keys_match?(labelset)
        rescue ArgumentError
          # If labelset contains keys that are a mixture of strings and symbols, this will
          # raise when trying to sort them, but the error should be the same:
          # InvalidLabelSetError
        end