Expression statement mode
-----
<?php
$a = $b;
yield $x;
-----
!!exprStmts
array(
    0: Stmt_Expression(
        expr: Expr_Assign(
            var: Expr_Variable(
                name: a
            )
            expr: Expr_Variable(
                name: b
            )
        )
    )
    1: Stmt_Expression(
        expr: Expr_Yield(
            key: null
            value: Expr_Variable(
                name: x
            )
        )
    )
)
-----
<?php
$a = $b
$c = $d
-----
!!exprStmts
Syntax error, unexpected T_VARIABLE from 3:1 to 3:2
Syntax error, unexpected EOF from 3:8 to 3:8
array(
    0: Stmt_Expression(
        expr: Expr_Assign(
            var: Expr_Variable(
                name: a
            )
            expr: Expr_Variable(
                name: b
            )
        )
    )
    1: Stmt_Expression(
        expr: Expr_Assign(
            var: Expr_Variable(
                name: c
            )
            expr: Expr_Variable(
                name: d
            )
        )
    )
)