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

Example Input: Sentence: 'a giraffe walking in its natural habitat on the savannah'. Replace the letter 't' with 'u' in the sentence.
Example Output: a giraffe walking in ius nauural habiuau on uhe savannah

Example Input: Sentence: 'a bathroom with a white toilet next to a large window'. Replace the letter 'w' with 'x' in the sentence.
Example Output: a bathroom xith a xhite toilet next to a large xindox

Example Input: Sentence: 'skateboarder jumping his board outdoors near a park bench'. Replace the letter 'r' with 'i' in the sentence.
Example Output:
skateboaidei jumping his boaid outdoois neai a paik bench