input: Write a function to take an integer input from the user and print its cube.
  
  assert cube_of_number("Please enter a number: 2")=="The cube of the number is: 8"
  assert cube_of_number("Please enter a number: 3")=="The cube of the number is: 27"
  assert cube_of_number("Please enter a number: 0")=="The cube of the number is: 0"
  assert cube_of_number("Please enter a number: -1")=="The cube of the number is: -1"
  assert cube_of_number("Please enter a number: 5")=="The cube of the number is: 125"
output: def cube_of_number(input_str):
      number = int(input_str.split(": ")[1])
      return f"The cube of the number is: {number**3}"