class TagObj:
   "class presenting tag related methods"
#
   def tagInsert(self, tag):
      if self.tagList.count(tag) == 0: # if doesn't exists,
         self.tagList.append(tag)      #  insert it!
#
   def tagRemove(self, tag):
      if self.tagList.count(tag) > 0:  # if exists,
         self.tagList.remove(tag)      #  remove it!
#
# Returns true (i.e., one) if object has tag
#
   def tagHas(self, tag):
      return self.tagList.count(tag)
#
# Returns tag list
#
   def tagCollection(self):
      return self.tagList
#
# Returns all objects from objList with same tags as object
#
   def tagSimilar(self, objList):
      newList = []
      for obj in objList: 
         missedTag = 0
         for tag in obj.tagList:
            if self.tagList.count(tag) == 0:
               missedTag = 1
               break
         if missedTag == 0 and obj.tagList != []:
            newList.append(obj)
      return newList
#
# Returns all objects from objList with at least one tag as object
#
   def tagRelated(self, objList):
      newList = []
      for obj in objList: 
         hasTag = 0
         for tag in obj.tagList:
            if self.tagList.count(tag) > 0:
               hasTag = 1
               break
         if hasTag == 1:
            newList.append(obj)
      return newList
#
#  Returns all tags that object has, that are related to 
#   at least one other object from objList
#
   def tagListAg(self, objList):
      newList = []
      for obj in objList:
         for tag in obj.tagList:
            if self.tagList.count(tag) > 0 and \
               newList.count(tag) == 0:
               newList.append(tag)         
      return newList
#
   def __init__(self):
      self.tagList = []

#############################################

x = TagObj()
y = TagObj()
z = TagObj()

x.tagInsert('old')
x.tagInsert('solid')
x.tagInsert('light')
y.tagInsert('new')
y.tagInsert('solid')
z.tagInsert('light')

print '='*40
print x.tagCollection()
print y.tagCollection()
print '-'*40
print x.tagSimilar([x,y,z])
print x.tagRelated([y])
print '-'*40
if x.tagHas('old'):
   print x.tagListAg([y,z])