Why there is a star inside randn?

[new_to_python]

Hi, I have question about generating a linear model from random data. I suppose that by default, the value of size in the dnorm function is one. When this function is called with N=100, size becomes 100. Am I correct? If so, what is the reason for having the * symbol in np.randn(*size)? What is the different between this and np.randn(size)?

def dnorm(mean, variance, size=1):
  if isinstance(size, int):
      size = size,
  return mean + np.sqrt(variable) * np.random.randn(*size)

N = 100
X = np.c_[dnorm(0, 0.4, size=N),
          dnorm(0, 0.6, size=N)]