input: Write a python function to generate a mixture of two normal distributions.
  assert len(random_mixture(0, 10, 1, 1, 1000)) == 1000
  assert all(isinstance(x, float) for x in random_mixture(0, 10, 1, 1, 10))
  assert len(random_mixture(5, -5, 2, 2, 500)) == 500
output: import numpy as np
  
  def random_mixture(mean1, mean2, std1, std2, size):
      mix = np.random.choice([0, 1], size=size)
      samples1 = np.random.normal(loc=mean1, scale=std1, size=size)
      samples2 = np.random.normal(loc=mean2, scale=std2, size=size)
      return [samples1[i] if mix[i] == 0 else samples2[i] for i in range(size)]