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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 find_rdataset(self, rdclass, rdtype, covers=dns.rdatatype.NONE, create=False):
 """Find an rdataset matching the specified properties in the current node. @param rdclass: The class of the rdataset @type rdclass: int @param rdtype: The type of the rdataset @type rdtype: int @param covers: The covered type. Usually this value is dns.rdatatype.NONE, but if the rdtype is dns.rdatatype.SIG or dns.rdatatype.RRSIG, then the covers value will be the rdata type the SIG/RRSIG covers. The library treats the SIG and RRSIG types as if they were a family of types, e.g. RRSIG(A), RRSIG(NS), RRSIG(SOA). This makes RRSIGs much easier to work with than if RRSIGs covering different rdata types were aggregated into a single RRSIG rdataset. @type covers: int @param create: If True, create the rdataset if it is not found. @type create: bool @raises KeyError: An rdataset of the desired type and class does not exist and I{create} is not True. @rtype: dns.rdataset.Rdataset object """


        for rds in self.rdatasets:
            if rds.match(rdclass, rdtype, covers):
                return rds
        if not create:
            raise KeyError
        rds = dns.rdataset.Rdataset(rdclass, rdtype)
        self.rdatasets.append(rds)
        return rds