Function decode_variable_int 

pub fn decode_variable_int<B>(buf: &mut B) -> Result<u32, MqttError>
where
    B: Buf,

Decodes a variable byte integer from the buffer (compatibility function)

This function provides compatibility with the old variable_byte module API. Prefer using VariableInt::decode(buf)?.value() for new code.

Errors

Returns an error if decoding fails