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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 read_file(filename):
 """Reads a file which matches the pattern `filename`. Args: filename The filename pattern Returns: The file content or the empty string, if the file is not found. """

    hits = glob.glob('**/{}'.format(filename), recursive=True)
    if not len(hits):
        pf.debug('No file "{}" found.'.format(filename))
        return ''
    elif len(hits) > 1:
        pf.debug('File pattern "{}" ambiguous. Using first.'.format(filename))

    with open(hits[0], 'r') as f:
        return f.read()