Update simple-serialize.md

specs/simple-serialize.md

@@ -74,19 +74,17 @@ return b"\x01" if value is True else b"\x00"
 ### Vectors, containers, lists
 
 ```python
-# Reccursively serialize fixed-size elements
+# Reccursively serialize
 fixed_parts = [serialize(element) if is_fixed_size(element) else None for element in value]
-fixed_lengths = [len(part) if part != None else BYTES_PER_LENGTH_PREFIX for part in fixed_parts]
-
-# Reccursively serialize variable-size elements
 variable_parts = [serialize(element) if is_variable_size(element) else None for element in value]
+
+# Compute and check lengths
+fixed_lengths = [len(part) if part != None else BYTES_PER_LENGTH_PREFIX for part in fixed_parts]
 variable_lengths = [len(part) if part != None else 0 for part in variable_parts]
-
-# Compute offsets of variable-size elements
 assert sum(fixed_lengths + variable_lengths) < 2**(BYTES_PER_LENGTH_PREFIX * BITS_PER_BYTE)
-offsets = [sum(fixed_lengths) + sum(variable_lengths[:i]) for i in range(len(value))]
 
-# Interleave offsets with fixed parts
+# Compute offsets of variable-size elements, and interleave with fixed parts
+offsets = [sum(fixed_lengths) + sum(variable_lengths[:i]) for i in range(len(value))]
 fixed_parts = [part if part != None else offsets[i] for i, part in enumerate(fixed_parts)]
 
 # Return the fixed parts (with offsets interleaved) followed by variable parts