Declare an interface named speaker with a method named speak. Declare a struct named english that represents a person who speaks english and declare a struct named chinese for someone who speaks chinese. Implement the speaker interface for each struct using a value receiver and these literal strings "Hello World" and "你好世界". Declare a variable of type speaker and assign the address of a value of type english and call the method. Do it again for a value of type chinese.
Add a new function named sayHello that accepts a value of type speaker. Implement that function to call the speak method on the interface value. Then create new values of each type and use the function.