A Tensor of type string.
The strings for which to compute the length for each element.
unit
An optional string from: "BYTE", "UTF8_CHAR". Defaults to "BYTE".
The unit that is counted to compute string length. One of: "BYTE" (for
the number of bytes in each string) or "UTF8_CHAR" (for the number of UTF-8
encoded Unicode code points in each string). Results are undefined
if unit=UTF8_CHAR and the input strings do not contain structurally
valid UTF-8.