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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def pprint_blockers(blockers):
 """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. """

    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