Function swap 

pub fn swap(
    token_program_id: &Pubkey,
    swap_pubkey: &Pubkey,
    swap_authority_key: &Pubkey,
    user_authority_key: &Pubkey,
    source_pubkey: &Pubkey,
    swap_source_pubkey: &Pubkey,
    swap_destination_pubkey: &Pubkey,
    destination_pubkey: &Pubkey,
    admin_fee_destination_pubkey: &Pubkey,
    amount_in: u64,
    minimum_amount_out: u64,
) -> Result<Instruction, ProgramError>

Creates a ‘swap’ instruction.