This function is in the StandardRewards.sol contract.
function join(uint256 id, uint256 poolTokenAmount) external greaterThanZero(poolTokenAmount) nonReentrant \
This function is used to deposit Bancor pool tokens (bnTokens) into a rewards program.
This function requires approval to be set for the relevant pool tokens prior to calling the function.
The function accepts a reward program ID and the number of pool tokens as arguments, and does not return anything.
This is the ID of the rewards program.
The number of pool tokens.