Problem with script and typing

[Thaddeus L. Olczyk]

Here goes ( extraneous pruned ):

project =[]

class Project:
       def IsNull(self):
	return self.name==""
	project.append(self)

def FindProject(x):
    for project in projects:
        if project.name == x:
            return x
        null=Project("")
        projects.remove(null)

def is_project(s):
    if s[len(s)-3:] == 'prj':
        project=FindProject(s)
## error here
        if project.IsNull():
            project=Project(s)
        project.Scan()
----------
error message AttributeError: 'None' object has no attribute 'IsNull'

Several questions.
1) I've banged my head against this type of typing problem before.
    How do I get around it?
2) Is there a better way of handling null objects? ( Most languages I 
    know have objects which are explicitly null )