# System.Text

``` diff
 namespace System.Text {
     public sealed class StringBuilder : ISerializable {
+        public StringBuilder Replace(ReadOnlySpan<char> oldValue, ReadOnlySpan<char> newValue);
+        public StringBuilder Replace(ReadOnlySpan<char> oldValue, ReadOnlySpan<char> newValue, int startIndex, int count);
     }
 }
```

