<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def removeAssociation(self, server_url, handle):
 """Remove an association if it exists. Do nothing if it does not. (str, str) -> bool """

        assoc = self.getAssociation(server_url, handle)
        if assoc is None:
            return 0
        else:
            filename = self.getAssociationFilename(server_url, handle)
            return _removeIfPresent(filename)