input: Write a function to modify the following Python code to raise an exception if the input value is not an integer. The original code takes a number `x` and returns its square root. If the input value is not an integer, a `TypeError` should be raised with the message 'Input must be an integer'.
  
  def square_root(x):
      if not isinstance(x, int):
          raise TypeError('Input must be an integer')
      return x**0.5
  
  assert square_root(4)==2.0
  assert square_root(25)==5.0
  assert square_root('4')
  assert square_root(2.5)
  assert square_root(9)==3.0
output: def square_root(x):
      if not isinstance(x, int):
          raise TypeError('Input must be an integer')
      return x**0.5