The final user function is called structure.superimpose. As the sequence alignment component of the
structure.align user function has been shifted into the new structure.sequence_alignment user
function and the information is now stored in ds.sequence_alignments relax data store object, the
functionality of structure.align and structure.superimpose are now essentially the same. The
sequence alignment arguments and documentation has also been eliminated. And the documentation has
been updated to say that sequence alignments from structure.sequence_alignment will be used for
superimposing the structures.
