You need to pass in the name and identifier parameters.
The name is the short name of the prefix mapping. That is, the prefix
itself, such as dc, as it might be used in a qualifier like dc.title.
The identifier is the name of the prefix mapping. That is,
typically, a URI permanently allocated to a specific qualifier
set, such as http://zthes.z3950.org/cql/1.0.
my $prefix = CQL::Prefix->new(
name => dc,
identifier => http://zthes.z3950.org/cql/1.0