Function spl_token::instruction::approve

pub fn approve(
    token_program_id: &Pubkey, 
    source_pubkey: &Pubkey, 
    delegate_pubkey: &Pubkey, 
    owner_pubkey: &Pubkey, 
    signer_pubkeys: &[&Pubkey], 
    amount: u64
) -> Result<Instruction, ProgramError>

Creates an Approve instruction.