Arrow function
-----
<?php
fn($a)
=>
$a;
-----
$stmts[0]->expr->expr = new Expr\Variable('b');
-----
<?php
fn($a)
=>
$b;
-----
<?php
fn(
$a
) => $a;
-----
$stmts[0]->expr->params[] = new Node\Param(new Expr\Variable('b'));
-----
<?php
fn(
$a, $b
) => $a;
-----
<?php
fn(
$a
)
=>
$a;
-----
// TODO: Format preserving currently not supported
$stmts[0]->expr->params = [];
-----
<?php
fn() => $a;
-----
<?php
fn($a)
: int
=> $a;
-----
$stmts[0]->expr->returnType = new Node\Identifier('bool');
-----
<?php
fn($a)
: bool
=> $a;
-----
<?php
fn($a)
: int
=> $a;
-----
$stmts[0]->expr->returnType = null;
-----
<?php
fn($a)
=> $a;
-----
<?php
fn($a)
: int
=> $a;

static fn($a)
: int
=> $a;
-----
$stmts[0]->expr->static = true;
$stmts[1]->expr->static = false;
-----
<?php
static fn($a)
: int
=> $a;

fn($a)
: int
=> $a;
-----
<?php
fn($a)
: int
=> $a;

fn&($a)
: int
=> $a;
-----
// TODO: Format preserving currently not supported
$stmts[0]->expr->byRef = true;
$stmts[1]->expr->byRef = false;
-----
<?php
fn&($a): int => $a;

fn($a): int => $a;