Function load_program_with_pubkey 

pub fn load_program_with_pubkey<CB: TransactionProcessingCallback>(
    callbacks: &CB,
    program_runtime_environment: &ProgramRuntimeEnvironment,
    pubkey: &Pubkey,
    current_slot: Slot,
    execute_timings: &mut ExecuteTimings,
) -> Option<(Arc<ProgramCacheEntry>, Slot)>

Loads the program with the given pubkey.

If the account doesn’t exist it returns None. If the account does exist, it must be a program account (belong to one of the program loaders). Returns Some(InvalidAccountData) if the program account is Closed, contains invalid data or any of the programdata accounts are invalid.