title: RDFLib: Namespace prefixes in XML serialization
body: <p>In a Python script using <a href="http://www.rdflib.net/" rel="noreferrer">RDFLib 3.0</a>, I get the following XML-Output when serializing my triples:</p>
  
  <pre><code>&lt;rdf:RDF
    xmlns:_3="http://www.my-example.intra/ontologies/ci.owl#"
  &gt;
  </code></pre>
  
  <p>How can I define specific namespace prefixes for those anonymous _x-prefixes automatically assigned by RDFLib (or it's XML-Serializer respectively)? </p>
  
  <pre><code>&lt;rdf:RDF
    xmlns:ex="http://www.my-example.intra/ontologies/ci.owl#"
  &gt;
  </code></pre>
  
  <p>Many thanks in advance for your responses!</p>