input: Write a function to generate an array of random numbers in Python. The function should take an integer 'size' as input and return an array of random integers between 0 and 100. If 'size' is not provided, the function should default to generating an array of size 10.
  assert generate_random_array(10)
  assert generate_random_array()
  assert generate_random_array(5)
output: import random
  
  def generate_random_array(size=10):
      return [random.randint(0, 100) for _ in range(size)]