input: Write a function to perform string slicing in Python that takes a string, start index, and end index, then returns the slice of the string from the start index to the end index (exclusive).
  assert slicing("This is a slicing test", 8, 15) == "slicing"
  assert slicing("Hello World", 6, 11) == "World"
  assert slicing("Python Programming", 0, 6) == "Python"
  assert slicing("Data Science", 5, 12) == "Science"
  assert slicing("", 0, 0) == ""
output: def slicing(s, start, end):
      return s[start:end]