human
Complete the below
def index_type(base_type, item):

    ''''Support array type creation by slicing, e.g. double[:, :] specifies
    a 2D strided array of doubles. The syntax is the same as for
    Cython memoryviews.'
    '''

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What is a the Python program you requested?
assistant
#Here is the Python program you requested.
    class InvalidTypeSpecification(Exception, ):
        pass
    def verify_slice(s):
        if (s.start or s.stop or (s.step not in (None, 1))):
            raise InvalidTypeSpecification('Only    a    step    of    1    may    be    provided    to    indicate    C    or    Fortran    contiguity')
    if isinstance(item, tuple):
        step_idx = None
        for (idx, s) in enumerate(item):
            verify_slice(s)
            if (s.step and (step_idx or (idx not in (0, (len(item) - 1))))):
                raise InvalidTypeSpecification('Step    may    only    be    provided    once,    and    only    in    the    first    or    last    dimension.')
            if (s.step == 1):
                step_idx = idx
        return _ArrayType(base_type, len(item), is_c_contig=(step_idx == (len(item) - 1)), is_f_contig=(step_idx == 0))
    elif isinstance(item, slice):
        verify_slice(item)
        return _ArrayType(base_type, 1, is_c_contig=bool(item.step))
    else:
        assert (int(item) == item)
        array(base_type, item)