input: Write a function to compress a given data sequence where consecutive numbers with the same sign or zero are grouped together. If the sequence is empty, return an empty list.
  
  def compress_sequence(nums):
      if not nums:
          return []
      
      output = []
      temp = [nums[0]]
  
      for i in range(1, len(nums)):
          if nums[i-1] * nums[i] >= 0:
              temp.append(nums[i])
          else:
              output.append(temp)
              temp = [nums[i]]
      output.append(temp)
  
      return output
  
  assert compress_sequence([9, -2, 6, 0, -7])==[[9], [-2], [6, 0], [-7]]
  assert compress_sequence([1, 2, -3, -4, 5, 0])==[[1, 2], [-3, -4], [5, 0]]
  assert compress_sequence([])==[]
  assert compress_sequence([0, 0, 0])==[[0, 0, 0]]
  assert compress_sequence([1, -1, 1, -1, 1])==[[1], [-1], [1], [-1], [1]]
output: def compress_sequence(nums):
      if not nums:
          return []
      
      output = []
      temp = [nums[0]]
  
      for i in range(1, len(nums)):
          if nums[i-1] * nums[i] >= 0:
              temp.append(nums[i])
          else:
              output.append(temp)
              temp = [nums[i]]
      output.append(temp)
  
      return output