input: Write a python function to convert temperatures between Celsius, Fahrenheit, and Kelvin.
  assert temperature_conversion(32, 'FtoC') == 0
  assert temperature_conversion(0, 'CtoF') == 32
  assert temperature_conversion(100, 'FtoK') == 310.92777777777775
  assert temperature_conversion(273.15, 'KtoC') == 0
  assert temperature_conversion(0, 'CtoK') == 273.15
  assert temperature_conversion(373.15, 'KtoF') == 212
output: def temperature_conversion(value, conversion_type):
      if conversion_type == 'FtoC':
          return (value - 32) * 5/9
      elif conversion_type == 'CtoF':
          return (value * 9/5) + 32
      elif conversion_type == 'FtoK':
          return (value - 32) * 5/9 + 273.15
      elif conversion_type == 'KtoC':
          return value - 273.15
      elif conversion_type == 'CtoK':
          return value + 273.15
      elif conversion_type == 'KtoF':
          return (value - 273.15) * 9/5 + 32