IDENTIFIER {ID_NONDIGIT}({ID_NONDIGIT}|{DIGIT})*
ESCSEQ \\(\'|\"|\?|\\|a|b|f|n|r|t|v|{OCTALDIGIT}{1,3}|u{HEXDIGIT}{4}|U{HEXDIGIT}{8}|x{HEXDIGIT}+)
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IDENTIFIER {ID_NONDIGIT}({ID_NONDIGIT}|{DIGIT})*
ESCSEQ \\(\'|\"|\?|\\|a|b|f|n|r|t|v|{OCTALDIGIT}{1,3}|u{HEXDIGIT}{4}|U{HEXDIGIT}{8}|x{HEXDIGIT}+)
%%