Basic unsigned-varint decoding.
Possible decoding errors.
Is this the last byte of an unsigned varint?
Decode the given slice as u8.
u8
Decode the given slice as u16.
u16
Decode the given slice as u32.
u32
Decode the given slice as u64.
u64
Decode the given slice as u128.
u128
Decode the given slice as usize.
usize