code: public ImmutableNamespaces withoutPrefix(String... prefixes) {
  		ImmutableNamespaces result=new ImmutableNamespaces(this.map);
  		for(String prefix:prefixes) {
  			result.map.remove(prefix);
  		}
  		return result;
  	}
docs: Create a copy of the namespaces without the prefixes.
  
  @param prefixes
  the prefixes to be excluded from the copy
  @return a copy of the instance that excludes the mappings for the
  specified prefixes.