@brief The assembler this parser will use to work on an assembly before matching against it.
@discussion <tt>preassembler</tt> should respond to the selector held by this parser's <tt>preassemblerSelector</tt> property.
@brief The method of <tt>preassembler</tt> this parser will call to work on an assembly.
@details The method represented by <tt>preassemblerSelector</tt> must accept a single <tt>TDAssembly</tt> argument. The signature of <tt>preassemblerSelector</tt> should be similar to: <tt>- (void)workOnAssembly:(TDAssembly *)a</tt>.