docs: def add(self, *blocks, indentation=0) -> "CodeBlock":
          """
          Adds sub-blocks at the specified indentation level, which defaults to 0.
  
          Nones are skipped.
  
          Returns the parent block itself, useful for chaining.
          """
          for block in blocks:
              if block is not None:
                  self._blocks.append((indentation, block))
  
          return self