input: Write a python function to find the parents of a given family from a database handle.
  assert family_label(None) == "Unknown"
  assert family_label(family_with_father_only) == "family_id : father's_name"
  assert family_label(family_with_mother_only) == "family_id : mother's_name"
  assert family_label(family_with_both_parents) == "family_id : father's_name and mother's_name"
output: def family_label(family):
      if family is None:
          return "Unknown"
      
      family_id = family.get("family_id", "Unknown")
      father = family.get("father")
      mother = family.get("mother")
  
      if father and mother:
          return f"{family_id} : {father} and {mother}"
      elif father:
          return f"{family_id} : {father}"
      elif mother:
          return f"{family_id} : {mother}"
      else:
          return family_id