Function mpl_token_auth_rules::processor::next_optional_account_info

pub fn next_optional_account_info<'a, 'b, I: Iterator<Item = &'a AccountInfo<'b>>>(
    iter: &mut I
) -> Result<Option<I::Item>, ProgramError>

Convenience function for accessing the next item in an AccountInfo iterator and validating whether the account is present or not.

This relies on the client setting the crate::id() as the pubkey for accounts that are not set, which effectively allows us to use positional optional accounts.