> Aztec.nr API reference, v6.0.0 (mainnet and testnet). Index: https://docs.aztec.network/aztec-nr-api/v6.0.0/llms.txt

# Module note

Module: `noir_aztec::history::note`

Note existence and non-nullification.

## Functions

- [assert_local_note_was_not_nullified_by](/aztec-nr-api/v6.0.0/noir_aztec/history/note/fn.assert_local_note_was_not_nullified_by.md): Asserts a note had **not** been nullified by a given block.
- [assert_local_note_was_nullified_by](/aztec-nr-api/v6.0.0/noir_aztec/history/note/fn.assert_local_note_was_nullified_by.md): Asserts a note had been nullified by a given block.
- [assert_local_note_was_valid_by](/aztec-nr-api/v6.0.0/noir_aztec/history/note/fn.assert_local_note_was_valid_by.md): Asserts a note existed and had not yet been nullified by a given block.
- [assert_note_existed_by](/aztec-nr-api/v6.0.0/noir_aztec/history/note/fn.assert_note_existed_by.md): Asserts that a note existed in the note hash tree by the time a block was mined.