eosio require_find

eosio::require_find is a function used in EOSIO smart contract development. It ensures the existence of a specific entry in a multi-index table by checking if the specified key exists within the table. This function takes two arguments:

1. const_iterator it: This parameter represents an iterator pointing to the entry within the multi-index table that corresponds to the provided key. If the entry exists, this iterator will point to it. If not found, it will point to the end of the table.

2. const Key& key: This is the key value for which existence is being checked within the multi-index table.

The purpose of eosio::require_find is to validate whether a particular entry exists in the table before performing operations on it. If the entry is not found, it results in an assertion failure, terminating the contract execution and preventing further processing. This helps to ensure that only existing and valid entries are accessed or manipulated within the smart contract.