code: public BasicBlock lookupBlockByLabel(int blockLabel) {
          for (Iterator<BasicBlock> i = blockIterator(); i.hasNext();) {
              BasicBlock basicBlock = i.next();
              if (basicBlock.getLabel() == blockLabel) {
                  return basicBlock;
              }
          }
          return null;
      }
docs: Look up a BasicBlock by its unique label.
  
  @param blockLabel
  the label of a BasicBlock
  @return the BasicBlock with the given label, or null if there is no such
  BasicBlock