tf.contrib.data.enumerate_dataset

tf.contrib.data.enumerate_dataset(
    start=0
)

# NOTE: The following examples use `{ ... }` to represent the
# contents of a dataset.
a = { 1, 2, 3 }
b = { (7, 8), (9, 10) }

# The nested structure of the `datasets` argument determines the
# structure of elements in the resulting dataset.
a.apply(tf.contrib.data.enumerate(start=5)) == { (5, 1), (6, 2), (7, 3) }
b.apply(tf.contrib.data.enumerate()) == { (0, (7, 8)), (1, (9, 10)) }