Sets children

        :param val: List of citation children

def children(self, val: list):
        """ Sets children

        :param val: List of citation children
        """
        final_value = []
        if val is not None:
            for citation in val:
                if citation is None:
                    continue
                elif not isinstance(citation, (BaseCitation, type(self))):
                    raise TypeError("Citation children should be Citation")
                else:
                    if isinstance(self, BaseCitation):
                        citation.root = self.root
                    else:
                        citation.root = self
                    final_value.append(citation)

        self._children = final_value