Your task is to implement a function replace_once(t, d), that takes a text t and a replacement dictionary d, and returns the result of replacing words according to the dictionary: if a word appears as a key, replace it with the dictionary value, and if a word does not appear in the dictionary, leave it alone.

Given a list of words, you can concatenate them together with spaces in between as follows:

word_list = "I love eating bananas".split()

print("Word list:", word_list)

back_together = " ".join(word_list)

print("Back together:", back_together)

# You can also join them in other ways, btw. Just DON'T do it for this homework.

print("You can also put commas:", ", ".join(word_list))

Here is where you can write your replace_once function.

def replace_once(t, d):

"""

@param t: a string

@param d: a dictionary, mapping words to their replacements

@returns: a string, where words in d have been replaced according to the dictionary mapping.

"""

# YOUR CODE HERE

raise NotImplementedError()