Can you give examples of popular interface contracts in programming?

In programming, interface contracts are agreements on how an interface should behave, what methods it should provide, and what guarantees it should fulfill. In Go, interfaces define a set of methods that a type must implement.

Examples of popular interface contracts in Go:

• io.Reader — an interface with the method Read(p []byte) (n int, err error), which describes a data source for reading.
• io.Writer — an interface with the method Write(p []byte) (n int, err error), describing a data sink for writing.
• fmt.Stringer — an interface with the method String() string, which allows a type to define its string representation.

These interfaces are widely used in the standard library and enable writing flexible and extensible code that works with any types implementing these contracts.