old_contents: from exchange import Exchange
  import sys
  import os
  
  def test_exchange_mif():
      A = 1e-11
      exchange = Exchange(A)
      mif_string = exchange.get_mif()
      lines = mif_string.split('\n')
      assert 'Specify Oxs_UniformExchange {' in lines[0]
      assert 'A' in lines[1]
      assert float(lines[1].split()[1]) == A
      assert '}' in lines[2]
  
  def test_exchange_formatting():
      A = 1e-11
      exchange = Exchange(A)
      mif_string = exchange.get_mif()
      assert mif_string[0] == 'S'
      assert mif_string[-1] == '\n'
      assert mif_string[-2] == '\n'
      
  
new_contents: from exchange import Exchange
  
  def test_exchange_mif():
      A = 1e-11
      exchange = Exchange(A)
      mif_string = exchange.get_mif()
      lines = mif_string.split('\n')
      assert 'Specify Oxs_UniformExchange {' in lines[0]
      assert 'A' in lines[1]
      assert float(lines[1].split()[1]) == A
      assert '}' in lines[2]
  
  def test_exchange_formatting():
      A = 1e-11
      exchange = Exchange(A)
      mif_string = exchange.get_mif()
      assert mif_string[0] == 'S'
      assert mif_string[-1] == '\n'
      assert mif_string[-2] == '\n'
      
  
subject: Remove imports.