def unescape_single_character(match):
value = match.group(<NUM_LIT:0>)<EOL>assert value.startswith("<STR_LIT:\\>")<EOL>return MYSQL_STRING_ESCAPE_SEQUENCE_MAPPING.get(value) or value[<NUM_LIT:1>:]<EOL>
Unescape a single escape sequence found from a MySQL string literal,
according to the rules defined at:
https://dev.mysql.com/doc/refman/5.6/en/string-literals.html#character-escape-sequences

:param match: Regular expression match object.

:return: Unescaped version of given escape sequence.
:rtype: str