Why does the 22 line not work

Question

from Queue import priorityQueue

class state(object):
def __init__(self,value,parent,
start = 0, goal = 0, solover = 0):
self.children = []
self.parent = parent
self.value = value
self.dist = 0
if parent:
self.path = parent.path[:]
self.path.append(value)
self.start = parent.start
self.goal = parent.goal
self.solver = parent.solver
else:
self.path = [value]
self.start = start
self.goal = goal
self.solver = solver

def GetDist(self):
pass
def creatchildren(self):
pass

class State_String(State):
def__init__(self, value, parent, start == 0, goal == 0):

super(State_String, self).__init__(value,
parent, start, goal)
self.dist = self.GetDist()

def GetDist(self):
if self.value == self.goal:
return 0
dist = 0
for i in range(len(self.goal)):
letter = self.goal[i]
dist += abs(i - self.value.index(letter))
return dist
def CreateChildren(self):
if not self.childern
for i in xrange(len(self.goal)-1):
val = self.value
val = val[:i] + val[i+1] + val[i] + val
child = State.String(val, self)
self.children.append(child)

Answer 1

I notice you have conditional '==' in your init, not sure if a typo but they should be only one = to be an optional argument.
which line is your line 22 and what error are you getting?
could you also show the initialisation of your State_String class object. I.e
x = State_String(1, self, start = 2)
not near a computer to pop the code in and test so need a little more info to know why it is failing for you.
in your state class you have parent being a required argument however you test if parent was supplied. Is this what you expect or maybe you might want to make it optional?