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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 prefixed_name(self) -> Tuple[YangIdentifier, Optional[YangIdentifier]]: """Parse identifier with an optional colon-separated prefix."""

        i1 = self.yang_identifier()
        try:
            next = self.peek()
        except EndOfInput:
            return (i1, None)
        if next != ":":
            return (i1, None)
        self.offset += 1
        return (self.yang_identifier(), i1)