docs: def vcfunpackinfo(table, *keys):
      """
      Unpack the INFO field into separate fields. E.g.::
  
          >>> import petl as etl
          >>> # activate bio extensions
          ... import petlx.bio
          >>> table1 = (
          ...     etl
          ...     .fromvcf('fixture/sample.vcf', samples=None)
          ...     .vcfunpackinfo()
          ... )
          >>> table1
          +-------+---------+-------------+-----+--------+------+---------+------+------+----------------+------+------+------+------+------+
          | CHROM | POS     | ID          | REF | ALT    | QUAL | FILTER  | AA   | AC   | AF             | AN   | DB   | DP   | H2   | NS   |
          +=======+=========+=============+=====+========+======+=========+======+======+================+======+======+======+======+======+
          | '19'  |     111 | None        | 'A' | [C]    |  9.6 | None    | None | None | None           | None | None | None | None | None |
          +-------+---------+-------------+-----+--------+------+---------+------+------+----------------+------+------+------+------+------+
          | '19'  |     112 | None        | 'A' | [G]    |   10 | None    | None | None | None           | None | None | None | None | None |
          +-------+---------+-------------+-----+--------+------+---------+------+------+----------------+------+------+------+------+------+
          | '20'  |   14370 | 'rs6054257' | 'G' | [A]    |   29 | []      | None | None | [0.5]          | None | True |   14 | True |    3 |
          +-------+---------+-------------+-----+--------+------+---------+------+------+----------------+------+------+------+------+------+
          | '20'  |   17330 | None        | 'T' | [A]    |    3 | ['q10'] | None | None | [0.017]        | None | None |   11 | None |    3 |
          +-------+---------+-------------+-----+--------+------+---------+------+------+----------------+------+------+------+------+------+
          | '20'  | 1110696 | 'rs6040355' | 'A' | [G, T] |   67 | []      | 'T'  | None | [0.333, 0.667] | None | True |   10 | None |    2 |
          +-------+---------+-------------+-----+--------+------+---------+------+------+----------------+------+------+------+------+------+
          ...
  
      """
  
      result = etl.unpackdict(table, 'INFO', keys=keys)
      return result