def METHOD_NAME(self):
    """Remove a single sequence from the CourseOutlineData (creates a copy)."""
    seq_to_remove = self.course_outline.sections[0].sequences[0]
    new_outline = self.course_outline.remove({seq_to_remove.usage_key})
    assert self.course_outline != new_outline
    assert seq_to_remove.usage_key in self.course_outline.sequences
    assert seq_to_remove.usage_key not in new_outline.sequences
    assert len(new_outline.sections[0].sequences) == len(self.course_outline.sections[0].sequences) - 1
    for seq in new_outline.sections[0].sequences:
        assert seq != seq_to_remove