Task: Program Execution
Input (English): Sentence: 'two sandwiches on whole wheat bread filled with meat slices, cheddar cheese slices, alfalfa sprouts and green leafy lettuce'. Replace the letter 'i' with 'x' in the sentence.
Output (English): two sandwxches on whole wheat bread fxlled wxth meat slxces, cheddar cheese slxces, alfalfa sprouts and green leafy lettuce