convert a phone number with alphabets in it to proper numbers

gistfile2.txt

txt2ph.py

MAPPING = {
    tuple('abcABC'): 2,
    tuple('defDEF'): 3,
    tuple('ghiGHI'): 4,
    tuple('jklJKL'): 5,
    tuple('mnoMNO'): 6,
    tuple('pqrsPQRS'): 7,
    tuple('tuvTUV'): 8,
    tuple('wxyzWXYZ'): 9,
}

def proper_dict(dictionary, sequence_of_keys, value):
    for each in sequence_of_keys:
        dictionary.update({each: value})


def convert(digit, dictionary):
    if str.isalpha(digit): return str(dictionary.get(digit, ""))
    else: return digit

if __name__ == '__main__':
    import sys
    phone = sys.argv[1]
    d = dict()
    [proper_dict(d, key, value) for key, value in MAPPING.items()]
    print "".join([convert(each, d) for each in phone])