whole_func_string: function FormatError(func, msg, value) {
  
          this.name = 'FormatError';
          this.message = new Formatter()(msg, value);
          if (Error.captureStackTrace) {
              Error.captureStackTrace(this, func);
          }
  
      }
func_code_string: function FormatError(func, msg, value) {
  
          this.name = 'FormatError';
          this.message = new Formatter()(msg, value);
          if (Error.captureStackTrace) {
              Error.captureStackTrace(this, func);
          }
  
      }
func_documentation_string: Custom Error Type