input: Write a function to find the largest number in a given list. The function should take a list of numbers as input and return the largest number in the list. If the list is empty, the function should return None.
  assert find_largest_number([1000, 506, 299, 620, 35])==1000
  assert find_largest_number([-1, -2, -3, -4, -5])==-1
  assert find_largest_number([1])==1
  assert find_largest_number([])==None
output: def find_largest_number(numbers):
      if not numbers:
          return None
      return max(numbers)