input: def compress_sequence(nums):
      """Compress a given data sequence by grouping consecutive numbers with the same sign.
      If two consecutive numbers are both positive or both negative, they are grouped together.
      If they have different signs, they are placed in separate groups.
      
      >>> compress_sequence([9, -2, 6, 0, -7])
      [[9], [-2, 6, 0], [-7]]
      """
      output = []
      temp = []
  
      for i in range(1, len(nums)):
          if nums[i-1] * nums[i] >= 0:
              temp.append(nums[i-1])
          else:
              temp.append(nums[i-1])
              output.append(temp)
              temp = []
      temp.append(nums[i])
      output.append(temp)
  
      return output
output:     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