code: def unique(table, key=None, presorted=False, buffersize=None, tempdir=None,
             cache=True):
      
  
      return UniqueView(table, key=key, presorted=presorted, 
                        buffersize=buffersize, tempdir=tempdir, cache=cache)
docs: Select rows with unique values under a given key (or unique rows
      if no key is given). E.g.::
  
          >>> import petl as etl
          >>> table1 = [['foo', 'bar', 'baz'],
          ...           ['A', 1, 2],
          ...           ['B', '2', '3.4'],
          ...           ['D', 'xyz', 9.0],
          ...           ['B', u'3', u'7.8'],
          ...           ['B', '2', 42],
          ...           ['E', None, None],
          ...           ['D', 4, 12.3],
          ...           ['F', 7, 2.3]]
          >>> table2 = etl.unique(table1, 'foo')
          >>> table2
          +-----+------+------+
          | foo | bar  | baz  |
          +=====+======+======+
          | 'A' |    1 |    2 |
          +-----+------+------+
          | 'E' | None | None |
          +-----+------+------+
          | 'F' |    7 |  2.3 |
          +-----+------+------+
          
      If `presorted` is True, it is assumed that the data are already sorted by
      the given key, and the `buffersize`, `tempdir` and `cache` arguments are
      ignored. Otherwise, the data are sorted, see also the discussion of the
      `buffersize`, `tempdir` and `cache` arguments under the
      :func:`petl.transform.sorts.sort` function.
  
      See also :func:`petl.transform.dedup.duplicates` and
      :func:`petl.transform.dedup.distinct`.