input: Write a function to perform string slicing in Python that takes a string and a start and end index, and returns the slice.
  assert slicing("This is a slicing test", 5, 7)=="is"
  assert slicing("Python Programming", 7, 18)=="Programming"
  assert slicing("Language Processing", 0, 8)=="Language"
  assert slicing("Simple Example", 0, 0)==""
  assert slicing("Error Handling", 5, 12)=="Handl"
output: def slicing(s, start, end):
      return s[start:end]