See Image for question.  from collections import namedtuple #----------------------------------------------------------------------- class Person():     # Stores info about a single person     # Created when an Individual (INDI) GEDCOM record is processed.     #-------------------------------------------------------------------     def __init__(self,ref):         # Initializes a new Person object, storing the string (ref) by         # which it can be referenced.         self._id = ref         self._asSpouse = []  # use a list to handle multiple families         self._asChild = None                      def addName(self, names):         # Extracts name parts from a list of names and stores them         self._given = names[0]         self._surname = names[1]         self._suffix = names[2]     def addIsSpouse(self, famRef):         # Adds the string (famRef) indicating family in which this person         # is a spouse, to list of any other such families         self._asSpouse.append(famRef)              def addIsChild(self, famRef):         # Stores the string (famRef) indicating family in which this person         # is a child         self._asChild = famRef def printDescendants(self, prefix=''):         # print info for this person and then call method in Family         print(prefix + self.name())         # recursion stops when self is not a spouse         for fam in self._asSpouse:             families[fam].printFamily(self._id,prefix)     def name (self):         # returns a simple name string          return self._given + ' ' + self._surname.upper()\                + ' ' + self._suffix          def treeInfo (self):         # returns a string representing the structure references included in self         if self._asChild: # make sure value is not None             childString = ' | asChild: ' + self._asChild         else: childString = ''         if self._asSpouse != []: # make sure _asSpouse list is not empty             # Use join() to put commas between identifiers for multiple families             # No comma appears if there is only one family on the list             spouseString = ' | asSpouse: ' + ','.join(self._asSpouse)         else: spouseString = ''         return childString + spouseString          def eventInfo(self):         ## add code here to show information from events once they are recognized         return ''     def __str__(self):         # Returns a string representing all info in a Person instance         # When treeInfo is no longer needed for debugging it can          return self.name() \                 + self.eventInfo()  \                 + self.treeInfo()  ## Comment out when not needed for debugging # Declare a named tuple type used by Family to create a list of spouses Spouse = namedtuple('Spouse',['personRef','tag']) class Family():     # Stores info about a family     # An instance is created when an Family (FAM) GEDCOM record is processed.     #-------------------------------------------------------------------     def __init__(self, ref):         # Initializes a new Family object, storing the string (ref) by         # which it can be referenced.         self._id = ref         self._spouse1 = None         self._spouse2 = None         self._children = []         self._asSpouse = []     def addSpouse(self, personRef, tag):         # Stores the string (personRef) indicating a spouse in this family         newSpouse = Spouse(personRef, tag)         if self._spouse1 == None:             self._spouse1 = newSpouse         else: self._spouse2 = newSpouse     def addChild(self, personRef):         # Adds the string (personRef) indicating a new child to the list         self._children.append(personRef) def printFamily(self, firstSpouse, prefix):         # Used by printDecendants in Person to print other spouse         # and recursively invoke printDescendants on children         # Manipulate prefix to prepare for adding a spouse and children         if prefix != '': prefix = prefix[:-2]+'  '                  # Print out a '+' and the name of the second spouse, if present         if self._spouse2:  # check for the presence of a second spouse             # If a second spouse is included, figure out which is the             # "other" spouse relative to the descendant firstSpouse             if self._spouse1.personRef == firstSpouse:                 secondSpouse = self._spouse2.personRef             else: secondSpouse = self._spouse1.personRef             print(prefix+ '+' + persons[secondSpouse].name())         # Make a recursive call for each child in this family         for child in self._children:              persons[child].printDescendants(prefix+'|--')