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

Example Input: Sentence: 'many people gathered on a sunny day flying kites'. Replace the letter 'e' with 'm' in the sentence.
Example Output: many pmoplm gathmrmd on a sunny day flying kitms

Example Input: Sentence: 'a crowd watches as giraffes graze the tree tops at the zoo'. Replace the letter 't' with 'q' in the sentence.
Example Output: a crowd waqches as giraffes graze qhe qree qops aq qhe zoo

Example Input: Sentence: 'a bathroom sink and mirror with a light that is on above it'. Replace the letter 'a' with 'z' in the sentence.
Example Output:
z bzthroom sink znd mirror with z light thzt is on zbove it