input: Write a python function to divide two numbers and handle division by zero.
  assert divide(10, 2) == "Result is 5.0"
  assert divide(10, 0) == "Divide by zero error!"
  assert divide(15, 3) == "Result is 5.0"
output: def divide(a, b):
      try:
          result = a / b
          return f"Result is {result}"
      except ZeroDivisionError:
          return "Divide by zero error!"