code: def p_const_vector_vector_list(p):
      
      if len(p[3]) != len(p[1][0]):
          syntax_error(p.lineno(2), 'All rows must have the same number of elements')
          p[0] = None
          return
  
      p[0] = p[1] + [p[3]]
docs: const_vector_list : const_vector_list COMMA const_vector