#!/usr/bin/env python
from __future__ import print_function
from __future__ import unicode_literals


class Graph(object):
    ''' Create an empty graph. '''
    def __init__(self):
        self.head = None

    def nodes():
        return nodes

    def edges():
        return edges

    def add_node(value):
        return

    def add_edge(value1, value2):
        return

    def del_node(value):
        return

    def has_node(value):
        return

    def neighbors(value):
        return neighbors

    def adjecent(value, value2):
        return condition

@@ -192,19 +192,33 @@
 elf.
-head = None
+graph = %7B%7D%0A        return
 %0A%0A  
@@ -306,32 +306,38 @@
 ef add_node(
+self, 
 value):%0A
         retu
@@ -316,32 +316,73 @@
 e(self, value):%0A
+        self.graph.setdefault(value, %5B%5D)%0A
         return%0A%0A
@@ -398,16 +398,22 @@
 dd_edge(
+self, 
 value1, 
@@ -450,24 +450,30 @@
 ef del_node(
+self, 
 value):%0A    
@@ -468,38 +468,143 @@
 value):%0A        
-return
+try:%0A            del self.graph%5Bvalue%5D%0A        except KeyError:%0A            raise KeyError('node not in graph')
 %0A%0A    def has_no
@@ -606,16 +606,22 @@
 as_node(
+self, 
 value):%0A
@@ -654,16 +654,22 @@
 ighbors(
+self, 
 value):%0A
@@ -711,16 +711,22 @@
 djecent(
+self, 
 value, v

add del_node function and add_node function.