Star Shorthand

Write a function that converts a string into star shorthand. If a character is repeated n times, convert it into character*n.

Examples

to_star_shorthand("abbccc") ➞ "ab*2c*3"

to_star_shorthand("77777geff") ➞ "7*5gef*2"

to_star_shorthand("abc") ➞ "abc"

to_star_shorthand("") ➞ ""

Notes

• Leave lone occurrences of a character as is.
• Return an empty string if given an empty string input.