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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def abook2vcf():
 """Command line tool to convert from Abook to vCard"""

    from argparse import ArgumentParser, FileType
    from os.path import expanduser
    from sys import stdout

    parser = ArgumentParser(description='Converter from Abook to vCard syntax.')
    parser.add_argument('infile', nargs='?', default=expanduser('~/.abook/addressbook'),
                        help='The Abook file to process (default: ~/.abook/addressbook)')
    parser.add_argument('outfile', nargs='?', type=FileType('w'), default=stdout,
                        help='Output vCard file (default: stdout)')
    args = parser.parse_args()

    args.outfile.write(Abook(args.infile).to_vcf())