`dns.name.Name`` or a ``str``.  If absolute, the
name must be a subdomain of the zone's origin.  If ``zone.relativize``
is ``True``, then the name will be relativized.

*rdtype*, a ``dns.rdataset.Rdataset`` or ``str``, the rdata type desired.

*covers*, a ``dns.rdataset.Rdataset`` or ``str``, 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.

*create*, a ``bool``.  If true, the node will be created if it does
not exist.

Returns a ``dns.rrset.RRset`` or ``None``.
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