text: Title: Add PartOfDay primitive
  Body: - Add a primitive that determine what part of the day a certain datetime falls in:
  
  ```python
  def day_part(hour):
      if hour in [4,5]:
          return "dawn"
      elif hour in [6,7]:
          return "early morning"
      elif hour in [8,9,10]:
          return "late morning"
      elif hour in [11,12,13]:
          return "noon"
      elif hour in [14,15,16]:
          return "afternoon"
      elif hour in [17, 18,19]:
          return "evening"
      elif hour in [20, 21, 22]:
          return "night"
      elif hour in [23,24,1,2,3]:
          return "midnight"
      
  ```