# check whether int conversion will raise an error, two examples.
# Python Idioms, http://jaynes.colorado.edu/PythonIdioms.html

#LBYL, test for the problematic conditions
def test_lbyl (a_str):
    if not isinstance(a_str, str) or not a_str.isdigit:
        return None
    elif len(a_str) > 10:    #too many digits for int conversion
        return None
    else:
        return int(a_str)

#EAFP, just try it, clean up any mess with handlers
def test_eafp(a_str):
    try:
        return int(a_str)
    except (TypeError, ValueError, OverflowError): #int conversion failed
        return None