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

Example Input: Sentence: 'people watching a kite being flown with a sky background'. Replace the letter 'a' with 'b' in the sentence.
Example Output: people wbtching b kite being flown with b sky bbckground

Example Input: Sentence: 'a room with a bed, lamps, tables and pillows'. Replace the letter 's' with 'b' in the sentence.
Example Output: a room with a bed, lampb, tableb and pillowb

Example Input: Sentence: 'people walk through a local fruit market in a city'. Replace the letter 'e' with 'n' in the sentence.
Example Output:
pnopln walk through a local fruit marknt in a city