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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def extract(self, member, path=None, pwd=None):
 """Extract single file into current directory. Parameters: member filename or :class:`RarInfo` instance path optional destination path pwd optional password to use """

        if isinstance(member, RarInfo):
            fname = member.filename
        else:
            fname = member
        self._extract([fname], path, pwd)