In this task, given a sentence in the English language, your task is to convert it into English Tokens.

Example Input: Prior to the arrival of troops, Haiti had not encountered problems related to the disease since the 1800s.
Example Output: Prior to the arrival of troops , Haiti had not encountered problems related to the disease since the 1800s .

Example Input: The canton in the north east of Switzerland has an area is 173 km².
Example Output: The canton in the north east of Switzerland has an area is 173 km ² .

Example Input: Additionally, a curfew has been imposed, and the military has closed Niger's borders.
Example Output:
Additionally , a curfew has been imposed , and the military has closed Niger 's borders .