Partition (split) each element around the right-most separator.
Calls str.rpartition element-wise.
For each element in a, split the element as the last occurrence of sep, and return 3 strings containing the part before the separator, the separator itself, and the part after the separator. If the separator is not found, return 3 strings containing the string itself, followed by two empty strings.
Right-most separator to split each element in array.
Output array of string or unicode, depending on input type. The output array will have an extra dimension with 3 elements per input element.