Expected `onClick` listener to be a function, instead got a value of `string` type. ``` class Square extends React.Component { getzhi(){ console.log('1') } render(){ return( <div> <button onClick="getzhi">{this.props.value}</button> </div> ) } } ``` ``` class Square extends React.Component { getzhi(){ console.log('1') } render(){ return( <div> <button onClick={this.getzhi}>{this.props.value}</button> </div> ) } } ``` ``` class Square extends React.Component { getzhi(){ console.log('1') } render(){ return( <div> <button onClick={this.getzhi}>{this.props.value}</button> </div> ) } } ``` ```