code: protected Expression string(int opPos) throws TransformerException
    {
      return compileUnary(new org.apache.xpath.operations.String(), opPos);
    }
docs: Compile a 'string(...)' operation.
  
  @param opPos The current position in the m_opMap array.
  
  @return reference to {@link org.apache.xpath.operations.String} instance.
  
  @throws TransformerException if a error occurs creating the Expression.