Fe does not support bytes, which leads to inconsistencies with Solidity.

```fe
contract C {
// TODO add storage variables

pub fn f(self, data: Bytes<100>) -> (u256, Bytes<100>) {
// TODO implement
}
}
```
```
fe build test.fe
```
```
error: undefined type
┌─ /mnt/sdd1/sbw/sol2rust/output/feTranslatorTest/failedfe/abi_decode_simple_1.fe:4:24
│
4 │ pub fn f(self, data: Bytes<100>) -> (u256, Bytes<100>) {
│ ^^^^^ `Bytes` has not been defined

error: undefined type
┌─ /mnt/sdd1/sbw/sol2rust/output/feTranslatorTest/failedfe/abi_decode_simple_1.fe:4:46
│
4 │ pub fn f(self, data: Bytes<100>) -> (u256, Bytes<100>) {
│ ^^^^^ `Bytes` has not been defined

```

Start by running `fe build test.fe` with the shown contract to reproduce the undefined `Bytes` errors. Trace how the compiler resolves the parameter and return types, then verify that `Bytes<100>` is accepted in both positions without the reported errors and remains consistent with Solidity expectations.

Written by the indexing model from the issue text.