ReactJS Uncaught ReferenceError function is not defined
<p>I am trying to implement a custom validation in React using ES6 syntax. </p>

<pre><code>import React, { Component } from 'react';

export default class Board extends Component {

    constructor(props) {
    super(props);
  }

  static propTypes = { count: validate };

  validate(props, propName, componentName){  
    if (props[propName]) {
      let value = props[propName];
      if (typeof value === 'number') {
          if (value &gt; 100) {
            return new Error("Value cannot be more than 100");
          }
      }
      else{
        return new Error('Count should be a number')
      }
    }
  };

  render() {
    return (
      &lt;div className="board"&gt;{this.props.count}&lt;/div&gt;
    );
  }
}
</code></pre>

<p>When I run this code, I get an error "Uncaught ReferenceError: validate is not defined". I will appreciate if someone could help me resolve this.</p>