code: def get_left_child(self, n):
          '''
          API: get_left_child(self, n)
          Description:
              Returns left child of node n. n can be Node() instance or string
              (name of node).
          Pre:
              Node n should be present in the tree.
          Input:
              n: Node name or Node() instance.
          Return:
              Returns name of the left child of n.
          '''
          if isinstance(n, Node):
              return n.get_attr('Lchild')
          return self.get_node_attr(n, 'Lchild'f get_left_child(self, n):
          '''
          API: get_left_child(self, n)
          Description:
              Returns left child of node n. n can be Node() instance or string
              (name of node).
          Pre:
              Node n should be present in the tree.
          Input:
              n: Node name or Node() instance.
          Return:
              Returns name of the left child of n.
          '''
          if isinstance(n, Node):
              return n.get_attr('Lchild')
          return self.get_node_attr(n, 'Lchild')
docs: API: get_left_child(self, n)
          Description:
              Returns left child of node n. n can be Node() instance or string
              (name of node).
          Pre:
              Node n should be present in the tree.
          Input:
              n: Node name or Node() instance.
          Return:
              Returns name of the left child of n.