code: def check_parent(self, parent_id, father = False):
          
          self.logger.debug("Checking parent {0}".format(parent_id))
          if parent_id != '0':
              if parent_id not in self.individuals:
                  raise PedigreeError(self.family_id, parent_id, 
                                      'Parent is not in family.')
              if father:
                  if self.individuals[parent_id].sex != 1:
                      raise PedigreeError(self.family_id, parent_id, 
                                          'Father is not specified as male.')
              else:
                  if self.individuals[parent_id].sex != 2:
                      raise PedigreeError(self.family_id, parent_id, 
                                          'Mother is not specified as female.')
          return
docs: Check if the parent info is correct. If an individual is not present in file raise exeption.
  
          Input: An id that represents a parent
                 father = True/False
  
          Raises SyntaxError if
              The parent id is not present
              The gender of the parent is wrong.