Heading
Small, medium and big section heading.
Create from string
php
$blocks = [
    Heading1::fromString("Heading 1"),
    Heading2::fromString("Heading 2"),
    Heading3::fromString("Heading 3"),
];

Create from RichText 
php
$block = Heading1::create(
    RichText::fromString("Heading "),
    RichText::fromString("with ")->italic(),
    RichText::fromString("Rich")->underline(),
    RichText::fromString("Text")->bold(),
);

Convert to string
php
$block = Heading1::create(
    RichText::fromString("Heading "),
    RichText::fromString("with ")->italic(),
    RichText::fromString("Rich")->underline(),
    RichText::fromString("Text")->bold(),
);
echo $block->toString();
Output:
Heading with RichText
Change text
php
$block = Heading1::fromString("Old heading");
$block = $block->changeText(
    RichText::fromString("New "),
    RichText::fromString("heading")->bold(),
);
echo $block->toString();
Output:
New heading
Add text
php
$block = Heading1::fromString("Heading");
$block = $block->addText(RichText::fromString(" extended"));
echo $block->toString();
Output
Heading extended
Notion SDK PHP