Add the following method to the Person class:

    // method to "multiply" 
    public Person Procreate(Person partner) 
    { 
      var baby = new Person  
      {  
        Name = $"Baby of {this.Name} and {partner.Name}"  
      }; 
      this.Children.Add(baby); 
      partner.Children.Add(baby); 
      return baby; 
    } 

At the top of the Program.cs file, type the following code to import the namespace for our class and statically import the Console type:

    using Packt.CS7; 
    using static System.Console; 

Now, we can get two people to make a baby by adding the following to the Main method of the Program.cs file:

    var harry = new Person { Name = "Harry" }; 
    var mary = new Person { Name = "Mary" }; 
    var baby1 = harry.Procreate(mary); 
    WriteLine($"{mary.Name} has {mary.Children.Count} children."); 
    WriteLine($"{harry.Name} has {harry.Children.Count} children."); 
    WriteLine($"{harry.Name}'s first child is named
    "{harry.Children[0].Name}"."); 

Run the console application and view the output:

Mary has 1 children.
Harry has 1 children.
Harry's first child is named "Baby of Harry and Mary".

An alternative would be to define an operator to allow two people to multiply. To allow this, we need to define a static operator for the * symbol inside the Person class:

    // operator to "multiply" 
    public static Person operator *(Person p1, Person p2) 
    { 
      return p1.Procreate(p2); 
    } 

Add the following code at the end of the Main method, but before writing the children, count to the console:

    var baby1 = harry.Procreate(mary); 
    var baby2 = harry * mary; 
    WriteLine($"{mary.Name} has {mary.Children.Count} children."); 

Run the application and view the output:

Mary has 2 children.
Harry has 2 children.
Harry's first child is named "Baby of Harry and Mary".