append vs leave off

append

verb
  • To add, as an accessory to the principal thing; to annex 

  • To write more data to the end of a pre-existing file, string, or other object. 

  • To hang or attach to, as by a string, so that the thing is suspended 

noun
  • An instance of writing more data to the end of an existing file. 

leave off

verb
  • To omit. 

  • To desist; to cease. 

  • To stop with a view to resuming at a later point. 

How often have the words append and leave off occurred in a corpus of books? (source: Google Ngram Viewer )