Fix str to byte concatenation  in Python 3
@@ -83,9 +83,9 @@ def encode(file, features):
parts.extend([_pack('>I', len(wkb)), wkb, _pack('>I', len(prop)), prop])
- body = _compress(_pack('>I', len(features)) + ''.join(parts))
+ body = _compress(_pack('>I', len(features)) + b''.join(parts))
- file.write('\x89MVT')
+ file.write(b'\x89MVT')
file.write(_pack('>I', len(body)))
file.write(body)
