In this task, you need to replace a letter in the sentence with another given letter.

Example Input: Sentence: 'a bunch of animals that are runing in a field'. Replace the letter 'm' with 'j' in the sentence.
Example Output: a bunch of anijals that are runing in a field

Example Input: Sentence: 'large stuffed toy bear sitting next to tree with assortment of bagged items'. Replace the letter 'y' with 'u' in the sentence.
Example Output: large stuffed tou bear sitting next to tree with assortment of bagged items

Example Input: Sentence: 'an elderly man watching a small girl with a frisbee clutched in her hand'. Replace the letter 'a' with 'z' in the sentence.
Example Output:
zn elderly mzn wztching z smzll girl with z frisbee clutched in her hznd