code: def pprint_blockers(blockers):
      
      pprinted = []
      for blocker in sorted(blockers, key=lambda x: tuple(reversed(x))):
          buf = [blocker[0]]
          if len(blocker) > 1:
              buf.append(' (which is blocking ')
              buf.append(', which is blocking '.join(blocker[1:]))
              buf.append(')')
          pprinted.append(''.join(buf))
      return pprinted
docs: Pretty print blockers into a sequence of strings.
  
      Results will be sorted by top-level project name. This means that if a
      project is blocking another project then the dependent project will be
      what is used in the sorting, not the project at the bottom of the
      dependency graph.