Is it possible to make python print a specified string if it get an error?

What I mean is, if for example I get an error like

Traceback (most recent call last):
  File "score_keeper-test.py", line 106, in <module>
    app = program()
  File "score_keeper-test.py", line 37, in __init__
    self.label1.set_text(team1_name)
TypeError: Gtk.Label.开发者_如何学Cset_text() argument 1 must be string, not None

Is there any way to make python print something like "You MUST enter a name in the TWO boxes" instead of the error above?

The Pythonic idiom is EAFP: easier to ask for forgiveness than permission. In this case:

try:
    self.label1.set_text(team1_name)
except TypeError:
    print "You MUST enter a name in the TWO boxes"

Note how I explicitly catch TypeError. This is recommended by PEP 8 -- Style Guide for Python Code (essential reading for any Python programmer):

When catching exceptions, mention specific exceptions whenever possible instead of using a bare except: clause.

An alternative (not-recommended) approach would be:

if team1_name:
    self.label1.set_text(team1_name)
else:
    print "You MUST enter a name in the TWO boxes"

...which is an example of LBYL: Look before you leap. This style can leave your code littered in if-statements.

if value:
   #Do stuff
else:
   print "You MUST enter a name in the TWO boxes"

Now, here, if the value is None, it will print the string - "You MUST enter a name in the TWO boxes"