/// <summary>
        /// Checks if a provided configuration file contains frequencies of processors
        /// </summary>
        /// <returns>
        /// An empty string if it is valid,
        /// an error message if invalid
        /// </returns>
        /// <param name="configFileContent">Content of a configuration file</param>
        public static string ContainsProcessorFrequencies(string configFileContent)
        {
            List <float>  processorFrequencies = ConfigFileParser.GetProcessorFrequencies(configFileContent);
            List <string> processorIds         = ConfigFileParser.GetProcessorIds(configFileContent);

            if (processorFrequencies.Count == 0 || processorIds.Count == 0 || processorFrequencies.Count != processorIds.Count)
            {
                return(ConfigErrors["ProcessorFrequencies"]);
            }
            else
            {
                // check if processor ids are unique
                if (processorIds.Distinct().Count() != processorIds.Count)
                {
                    return(ConfigErrors["ProcessorFrequenciesIds"]);
                }

                return("");
            }
        }