Example

$form->addHeading('Section 1');
$form->startFieldset();
$form->addHtml('<p class="text-muted pt-2 pb-5">// Section 1 content here ...</p>');
$form->endFieldset();

$form->addHeading('Section 2');
$form->startFieldset();
$form->addHtml('<p class="text-muted pt-2 pb-5">// Section 2 content here ...</p>');
$form->endFieldset();

$form->addHeading('Section 3');
$form->startFieldset();
$form->addHtml('<p class="text-muted pt-2 pb-5">// Section 3 content here ...</p>');
$form->endFieldset();

Your copy of PHP Form Builder is NOT authorized.
About PHP Form Builder License

Section 1

// Section 1 content here ...

Section 2

// Section 2 content here ...

Section 3

// Section 3 content here ...

<h4>
	<span class="js-badger-accordion-header">Section 1</span>
	</h4>
		<fieldset  class="badger-accordion__panel js-badger-accordion-panel -ba-is-hidden">
			<div class="js-badger-accordion-panel-inner">
				<p class="text-muted pt-2 pb-5">
					// Section 1 content here ...
					</p>
						</div>
							</fieldset>
								<h4>
									<span class="js-badger-accordion-header">Section 2</span>
									</h4>
										<fieldset  class="badger-accordion__panel js-badger-accordion-panel -ba-is-hidden">
											<div class="js-badger-accordion-panel-inner">
												<p class="text-muted pt-2 pb-5">
													// Section 2 content here ...
													</p>
														</div>
															</fieldset>
																<h4>
																	<span class="js-badger-accordion-header">Section 3</span>
																	</h4>
																		<fieldset  class="badger-accordion__panel js-badger-accordion-panel -ba-is-hidden">
																			<div class="js-badger-accordion-panel-inner">
																				<p class="text-muted pt-2 pb-5">
																					// Section 3 content here ...
																					</p>
																						</div>
																							</fieldset>