Python detecting error in code

This snippet of python code has a lot of errors, but I wanted to know if someone can specifically explain to me what the "No global traceback found" error and "self is not first method argument?" The following occur on lines 16 and 28 respectively.

 1   #! /usr/bin/env python
 2
 3   'Example errors caught by PyChecker'
 4
 5   import string
 6
 7   metaslash = 1
 8
 9   def printNames():
10       neal = 'neal'
11       michelle = 'michele'
12       eric = 5
13       print "Local values: %(neal)S %(michele)s %(eric)" % locals()
14
15   class Nothing:
16       def printValue(value):
17           print value
18       def set(self, value):
19           self.value = value
20
21   def tryToDoSomething(self, value):
22       try:
23           import string
24           if not value:
25               raise RuntimeError, "Hey, there's no value"
26           printNames('a, b, c')
27       except:
28           traceback.print_exc()
29
30   def setGlobal(value=None):
31       print 'Old MetaSlash value is:', metaslash
32       metaslash = value
33       useless = Nothing(5)
34       print 'a useless value is:', useless.valeu