
Backward Each Word

In a given string you should reverse every word, but the words should stay in their places.
Input: A string (str).
Output: A string (str).
Examples:
assert backward_string_by_word("") == "" assert backward_string_by_word("world") == "dlrow" assert backward_string_by_word("hello world") == "olleh dlrow" assert backward_string_by_word("hello world") == "olleh dlrow"
Precondition: The line consists only from alphabetical symbols and spaces.