How to use the @ckeditor/ckeditor5-utils/src/dom/indexof function in @ckeditor/ckeditor5-utils

domPositionToView( domParent, domOffset ) {
		if ( this.isBlockFiller( domParent, this.blockFillerMode ) ) {
			return this.domPositionToView( domParent.parentNode, indexOf( domParent ) );
		}

		// If position is somewhere inside UIElement - return position before that element.
		const viewElement = this.mapDomToView( domParent );

		if ( viewElement && viewElement.is( 'uiElement' ) ) {
			return ViewPosition._createBefore( viewElement );
		}

		if ( isText( domParent ) ) {
			if ( isInlineFiller( domParent ) ) {
				return this.domPositionToView( domParent.parentNode, indexOf( domParent ) );
			}

			const viewParent = this.findCorrespondingViewText( domParent );
			let offset = domOffset;

domPositionToView( domParent, domOffset ) {
		if ( this.isBlockFiller( domParent, this.blockFillerMode ) ) {
			return this.domPositionToView( domParent.parentNode, indexOf( domParent ) );
		}

		// If position is somewhere inside UIElement - return position before that element.
		const viewElement = this.mapDomToView( domParent );

		if ( viewElement && viewElement.is( 'uiElement' ) ) {
			return ViewPosition._createBefore( viewElement );
		}

		if ( isText( domParent ) ) {
			if ( isInlineFiller( domParent ) ) {
				return this.domPositionToView( domParent.parentNode, indexOf( domParent ) );
			}

			const viewParent = this.findCorrespondingViewText( domParent );
			let offset = domOffset;

			if ( !viewParent ) {
				return null;
			}

			if ( startsWithFiller( domParent ) ) {
				offset -= INLINE_FILLER_LENGTH;
				offset = offset < 0 ? 0 : offset;
			}

			return new ViewPosition( viewParent, offset );
		}

if ( !domBefore ) {
					// Position is after a view element that has not been rendered to DOM yet.
					return null;
				}

				domParent = domBefore.parentNode;
				domAfter = domBefore.nextSibling;
			}

			// If there is an inline filler at position return position inside the filler. We should never return
			// the position before the inline filler.
			if ( isText( domAfter ) && startsWithFiller( domAfter ) ) {
				return { parent: domAfter, offset: INLINE_FILLER_LENGTH };
			}

			const offset = domBefore ? indexOf( domBefore ) + 1 : 0;

			return { parent: domParent, offset };
		}
	}

domRoot.addEventListener( 'mousedown', evt => {
				if ( evt.target.classList.contains( 'magic-block' ) ) {
					const viewPosition = editingView.domConverter.domPositionToView( evt.target.parentNode, indexOf( evt.target ) );
					const modelPosition = editor.editing.mapper.toModelPosition( viewPosition );

					editor.model.change( writer => {
						const paragraph = writer.createElement( 'paragraph' );

						writer.insert( paragraph, modelPosition );
						writer.setSelection( paragraph, 0 );
					} );
				}
			} );
		} );