Unicode escape sequence
-----
<?php

"\u{0}";
"\u{114}";
"\u{1F602}";
-----
!!php7
array(
    0: Stmt_Expression(
        expr: Scalar_String(
            value: @@{"\0"}@@
        )
    )
    1: Stmt_Expression(
        expr: Scalar_String(
            value: Ĕ
        )
    )
    2: Stmt_Expression(
        expr: Scalar_String(
            value: @@{"\xF0\x9F\x98\x82"}@@
        )
    )
)