Function check_program 

pub fn check_program(
    account: &AccountView,
    expected_program_id: &Address,
) -> ProgramResult

Check that an account is a specific program: its key matches expected_program_id and it is flagged executable.

Matches the Jiminy-style free-function surface the winning- architecture design calls for. Equivalent to constructing a Program<'info, P> wrapper without requiring a generic ProgramId impl - useful for ad-hoc program pinning where the program ID is only known at runtime (for instance, a caller-supplied cross-program id).