Total bytes consumed by the elements of the array.
Does not include bytes consumed by the array mask
Examples
>>> d = cf.Data([[1, 1.5, 2]])
>>> d.dtype
dtype('float64')
>>> d.size, d.dtype.itemsize
(3, 8)
>>> d.nbytes
24
>>> d[0] = cf.masked
>>> print d.array
[[-- 1.5 2.0]]
>>> d.nbytes
24