input: Write a function to convert the given temperature from Celsius to Fahrenheit. The function should take the temperature in Celsius as an input and return the temperature in Fahrenheit.
  
  assert celsius_to_fahrenheit(0) == 32
  assert celsius_to_fahrenheit(100) == 212
  assert celsius_to_fahrenheit(-40) == -40
  assert celsius_to_fahrenheit(37) == 98.6
  assert celsius_to_fahrenheit(25) == 77
output: def celsius_to_fahrenheit(celsius):
      return celsius * 9/5 + 32