# define some sets
gis = set(['arcgis', 'mapinfo', 'qgis', 'grass', 'udig'])
opensource = set(['qgis', 'grass', 'udig'])
usingpython = set(['qgis', 'grass', 'arcgis'])


soft = 'arcgs'
if soft in gis:
    print 'it is a GIS software'
elif soft in opensource:
    print 'it is opensource'
elif soft in usingpython:
    print 'it use python'
else:
    print 'something else...'

usepython = True if soft in usingpython else False
print usepython

for soft in gis:
    print soft, '\n', '=' * len(soft)
    if soft in opensource:
        print 'it is opensource'
    else:
        print 'it is propretary'
    if soft in usingpython:
        print 'it use python'
    else:
        print 'it use something else'
    print '\n'

len_software = [(soft, len(soft)) for soft in gis]
len_software

len_software = [(soft, len(soft)) for soft in gis if soft in opensource]
len_software

contact = {'pietro': 333123808, 'jonh': 123123123}



x = 0
while x < 4:
    print 'a' * x
    x += 1

for soft in gis:
    print soft, '\n', '=' * len(soft)
    if soft in opensource:
        print 'it is opensource'
        break
    else:
        print 'it is propretary'
    if soft in usingpython:
        print 'it use python'
        continue
    else:
        print 'it use something else'
    print '\n'

numerator = 1
denominator = 0.5 # change to 0
try:
    print numerator/denominator
except ZeroDivisionError:
    print "Divide a number with 0 is not a valid operation!"