Where does the toggleOpen function come from in this code?

Question

React

Good day to all. Tell me, how do we use the isOpen property and the toggleOpen function in this code, if they are not in the imports? The code of the entire training application is at the link
Thanks in advance.

import React, {Component, PureComponent} from 'react'
import {findDOMNode} from 'react-dom'
import {connect} from 'react-redux'
import PropTypes from 'prop-types'
import CommentList from '../CommentList'
import { CSSTransitionGroup } from 'react-transition-group'
import {deleteArticle, loadArticle} from '../../AC'
import Loader from '../Loader'
import LocalizedText from '../LocalizedText'
import './style.css'

class Article extends Component {
    static propTypes = {
        id: PropTypes.string.isRequired,
        isOpen: PropTypes.bool,
        toggleOpen: PropTypes.func,
        //from connect
        article: PropTypes.shape({
            id: PropTypes.string,
            title: PropTypes.string,
            text: PropTypes.string
        })
    }

    state = {
        updateIndex: 0,
        areCommentsOpen: false
    }

    componentDidMount() {
        const {loadArticle, article, id} = this.props
        if (!article  || (!article.text && !article.loading)) loadArticle(id)
    }

/*
    shouldComponentUpdate(nextProps, nextState) {
        return nextProps.isOpen !== this.props.isOpen
    }
*/

    render() {
        const {article, isOpen, toggleOpen} = this.props
        if (!article) return null
        return (
            <div ref = {this.setContainerRef}>
                <h3>{article.title}</h3>
                <button onClick = {this.handleDelete}><LocalizedText>delete me</LocalizedText></button>
                <CSSTransitionGroup
                    transitionName = 'article'
                    transitionAppear
                    transitionEnterTimeout = {300}
                    transitionLeaveTimeout = {500}
                    transitionAppearTimeout = {500}
                    component = 'div'
                >
                    {this.getBody()}
                </CSSTransitionGroup>
            </div>
        )
    }

    handleDelete = () => {
        const {deleteArticle, article} = this.props
        deleteArticle(article.id)
        console.log('---', 'deleting article')
    }

    setContainerRef = ref => {
        this.container = ref
//        console.log('---', ref)
    }

    getBody() {
        const {article, isOpen} = this.props
        if (!isOpen) return null
        if (article.loading) return <Loader/>
        return (
            <section>
               {article.text}
               <CommentList article = {article} ref = {this.setCommentsRef} key = {this.state.updateIndex}/>
            </section>
        )
    }

    setCommentsRef = ref => {
        this.comments = ref
//        console.log('---', ref)
    }
}

export default connect((state, ownProps) => {
        return {
            article: state.articles.entities.get(ownProps.id)
        }
    },
    { deleteArticle, loadArticle },
    null,
    { pure: false }
)(Article)

Answer 1

Where does the toggleOpen function come from in this code?

Obviously from the props.