public partial class Form1 : Form
   {
      public Form1()
      {
         InitializeComponent();
      }

      protected override void OnLoad(EventArgs e)
      {
         base.OnLoad(e);
         var token = new CancellationTokenSource().Token;
         Task.Factory.StartNew (() => {
            while (!token.IsCancellationRequested) {
               try {
                  if (/*Condition*/)
                     this.Invoke(new Action(() => label.Text = " =)"));
                  else
                     this.Invoke(new Action(() => label.Text = " =("));
                  Thread.Sleep(10);
               }
               catch (Exception) {
                  throw;
               }
               finally {
                  throw new Exception();
               }
            }
         }) ;
      }
   }

        public static bool ValidateEmailAddress(string emailAddress)
        {
            string pattern = "^((?>[a-zA-Z\\d!#$%&'*+\\-/=?^_`{|}~]+\x20*|\"((?=[\x01-\x7f])[^\"\\]|\\[\x01-\x7f])*\"\x20*)*(?<angle><))?((?!\\.)(?>\\.?[a-zA-Z\\d!#$%&'*+\\-/=?^_`{|}~]+)+|\"((?=[\x01-\x7f])[^\"\\]|\\[\x01-\x7f])*\")@(((?!-)[a-zA-Z\\d\\-]+(?<!-)\\.)+[a-zA-Z]{2,}|\\[(((?(?<!\\[)\\.)(25[0-5]|2[0-4]\\d|[01]?\\d?\\d)){4}|[a-zA-Z\\d\\-]*[a-zA-Z\\d]:((?=[\x01-\x7f])[^\\\\[\\]]|\\[\x01-\x7f])+)\\])(?(angle)>)$";

            if (!String.IsNullOrEmpty(emailAddress) && !(Regex.Match(emailAddress.Trim(), pattern, RegexOptions.IgnoreCase)).Success)
            {
                return false;
            }
            return true;
        }

if (date.Training != null)
            {
                var training = date.Training;
                var status = new TrainingStatus();
                var refresher = new Training();

                if (training.Trainings != null)
                    refresher = training.Trainings;

                bool hasTakenRefresher = false;
                status.Value = date.Date.AddDays(
                    TrainingHelper.CalculateValidityDays(training.Validity ?? 0, training.ValidityType ?? 0));

                status.Name = training.TrainingName;
                status.ID = training.TrainingID;
                status.Category = training.CategoryTraining != null ? training.CategoryTraining.Name : "Other";
                status.IsTrained = _validityUtilsService.IsValid(training, date.Date);

                if (status.IsTrained)
                {
                    status.IsExpiring = _validityUtilsService.IsExpiring(training, date.Date,
                                            TrainingHelper.CalculateValidityDays(
                                                training.ExpirationWarningValidity ?? 0,
                                                training.ExpirationWarningValidityType ?? 0));
                }

                if (refresher.ID != 0)
                {
                    hasTakenRefresher = employee.Dates
                        .Count(x => x.Training != null
                            && x.TrainingID == refresher.ID) > 1;

                    if (hasTakenRefresher && (status.IsExpiring || !status.IsTrained))
                    {
                        status.IsExpiring = false;
                        var trainingWithNewValidity = new Training();

                        status.Value = date.Date.AddDays(
                            TrainingHelper.CalculateValidityDays(training.ValidityRefresher ?? 0,
                                training.ValidityRefresherType ?? 0));

                        trainingWithNewValidity.Validity = training.ValidityRefresher;
                        trainingWithNewValidity.ValidityType = training.ValidityRefresherType;
                        status.IsTrained = _validityUtilsService.IsValid(trainingWithNewValidity, date.Date);

                        if (status.IsTrained)
                        {
                            status.IsExpiring = _validityUtilsService.IsExpiring(trainingWithNewValidity, date.Date,
                                TrainingHelper.CalculateValidityDays(
                                    refresher.ExpirationWarningValidity ?? 0,
                                    refresher.ExpirationWarningValidityType ?? 0));
                        }
                    }
                }

                if (status.IsTrained && !status.IsExpiring)
                    status.Status = TrainingStatuses.Trained;
                else if (status.IsTrained && status.IsExpiring)
                    status.Status = TrainingStatuses.Expiring;
                else if (!status.IsTrained && !status.IsExpiring)
                    status.Status = TrainingStatuses.Expired;

                status.EmpID = employee.ID;

                return status;
            }

// IsFooBar being a boolean, we check if it's different from true and from false
if (x.IsFooBar != true && x.IsFooBar != false)
{
    return "error";
}

public class MetricsChecker
{
    protected const string AwaitingRecognitionCountMetricName = "AwaitingRecognitionCount";
    protected const string AwaitingExportCountMetricName = "AwaitingExportCount";
    protected const string NotYetDownloadedEventCountMetricName = "NotYetDownloadedEventCount";
    
    ...
    
    public virtual void PublishNotYetDownloadedEventCounts()
    {
        this.logger.Trace($"Starting to gather and publish {NotYetDownloadedEventCountMetricName}(s).");
        ...
    }
    
    ...
}

var list = new List<string>() { // Assume some items in the list };

for (var i = 0; i < list.Count; i++)
{
    var item = list[i];
    list.Remove(item);
    
    i--;
}

string AllPDF = "";
int CountPDF = 0;
AllPDF = txtInput.Text;
string[] AllPDF2 = AllPDF.Split(';');
List<string> PDF = new List<string>();
PDF.AddRange(AllPDF2);
while (PDF.Count != CountPDF)
{
    File.Delete(AllPDF2[0 + CountPDF] + ".pdf");
	CountPDF++;
}

const int ONLY_ONE_ITEM = 1;

if (myList.Count > ONLY_ONE_ITEM)
{
    DoSomething();
}
else
{
    DoSomethingElse();
}

// Return flagged enum with inverted selected flag value
public static TEnum SwapFlag<TEnum>(this TEnum target, TEnum flag) where TEnum : Enum
    {
        if (target.HasFlag(flag)) return (TEnum)(object)((int)(object)target & ~(int)(object)flag);

        return (TEnum)(object)((int)(object)target | (int)(object)flag);
    }