Class 'Sequence' does not define '__add__', so the '+' operator cannot be used on its instances

The `Sequence` class in Python does not define the `__add__` method, which is necessary for using the `+` operator on its instances. The `__add__` method allows you to concatenate two sequences together. If you want to concatenate two sequences using the `+` operator, you need to convert the `Sequence` instances to a compatible type, such as a list, and then perform the concatenation. Here's an example:

sequence1 = Sequence(...)
sequence2 = Sequence(...)

# Convert the sequences to lists
list1 = list(sequence1)
list2 = list(sequence2)

# Concatenate the lists
result = list1 + list2

By converting the `Sequence` instances to lists, you can use the `+` operator to concatenate them.