input: Write a function to optimize a given multivariate function using SciPy's optimize module. The function should take the function to be optimized and an initial guess as input, and return the optimized values of the variables.
  # 
  assert optimize_function(lambda x: (x[0]-1)**2 + (x[1]-2)**2, [0, 0]) == [1, 2]
output: def optimize_function(func, initial_guess):
      from scipy.optimize import minimize
      result = minimize(func, initial_guess)
      return result.x