input: Write a function to find the mode of the given set of values. The mode is the value that appears most frequently in a list of numbers. If there are multiple modes, return the first one that appears. The function should take in a list of numbers as input and return the mode.
  assert find_mode([1, 2, 3, 2, 4, 2])==2
  assert find_mode([3, 5, 10, 1, 2])==3
  assert find_mode([4, 3, 1, 2])==4
  assert find_mode([3, 5, 4, 1, 2])==3
  assert find_mode([])==None
output: def find_mode(nums):
      if not nums:
          return None
      count = {}
      for num in nums:
          if num in count:
              count[num] += 1
          else:
              count[num] = 1
      mode = max(count, key=count.get)
      return mode