A type implements ABIDecodable must be a tuple of types implement
ABIVariable. For convenient, for the tuple with only one element like
(U256,), we implement ABIDecodable for U256 instead.
A type implements ABIEncodable must be a tuple of types implement
ABIVariable. For convenient, for the tuple with only one element like
(U256,), we implement ABIEncodable for U256 instead.
A type implements ABIPackedEncodable must be a tuple of types implement
ABIVariable. For convenient, for the tuple with only one element like
(U256,), we implement ABIPackedEncodable for U256 instead.
A type implements EventIndexEncodable must be a tuple of types implement
EventIndexEncodable. For convenient, for the tuple with only one element
like (U256,), we implement EventIndexEncodable for U256 instead.