What would you put instead of this C# code, in D?
```C#
// Arrange
const string templateString = "My {pet} has {number}
{ailment}.";
var pairs = new
{
pet = "dog",
number = 5,
ailment = "fleas",
};
// Act
var result =
TemplateStringInterpolator.ReplaceTokens(templateString, pairs);
// Assert
result.Should().Be("My dog has 5 fleas.");
```
I've made a function for strings:
```D
string replaceTokens(in string tmpString, in string[string] aa) {
import std.array : replace;
string result = tmpString;
foreach(key, value; aa) {
string addBits(in string root) {
return "{" ~ root ~ "}";
}
result = result.replace(addBits(key), value);
}
return result;
}
```
