input: Write a function to modify the following Python code to raise an exception if the input value is not an integer. If the input value is an integer, return the square root of the input.
  
  ### Input:
  def square_root(x):
      return x**0.5
  
  ### Output:
  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(9)==3.0
  assert square_root(16)==4.0
  assert square_root('4')==TypeError('Input must be an integer')
  assert square_root(4.0)==TypeError('Input must be an integer')
output: def square_root(x):
      if not isinstance(x, int):
          raise TypeError('Input must be an integer')
      return x**0.5