Blocked revisions 69070,69074 via svnmerge

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  r69070 | raymond.hettinger | 2009-01-28 17:02:26 -0600 (Wed, 28 Jan 2009) | 6 lines

  Issue 4920:  Fixed next() vs __next__() issues in the ABCs
  for Iterator and MutableSet.  Also added thorough test for
  required abstractmethods.
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  r69074 | raymond.hettinger | 2009-01-28 17:58:16 -0600 (Wed, 28 Jan 2009) | 1 line

  Correct docs for ABCs (MutableSequence was missing __setiem).  Simplify the table by taking out inherited requirements for abstract methods.
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