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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 check_manifest ():
 """Snatched from roundup.sf.net. Check that the files listed in the MANIFEST are present when the source is unpacked."""

    try:
        f = open('MANIFEST')
    except Exception:
        print('\n*** SOURCE WARNING: The MANIFEST file is missing!')
        return
    try:
        manifest = [l.strip() for l in f.readlines() if not l.startswith('#')]
    finally:
        f.close()
    err = [line for line in manifest if not os.path.exists(line)]
    if err:
        n = len(manifest)
        print('\n*** SOURCE WARNING: There are files missing (%d/%d found)!' %
            (n - len(err), n))
        print('\nMissing: '.join(err))