input: Write a python function to convert kilometers to miles.
  assert kms_to_miles(10) == 6.215040397762586
  assert kms_to_miles(5) == 3.107520198881293
  assert kms_to_miles(100) == 62.15040397762586
output: def kms_to_miles(kilometers):
      miles = kilometers * 0.6215040397762586
      return miles