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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 get(filename, ignore_fields=None):
 """ Get all entries from a BibTeX file. :param filename: The name of the BibTeX file. :param ignore_fields: An optional list of fields to strip from the BibTeX \ file. :returns: A ``bibtexparser.BibDatabase`` object representing the fetched \ entries. """

    # Handle default argument
    if ignore_fields is None:
        ignore_fields = []

    # Open bibtex file
    with open(filename, 'r') as fh:
        bibtex = bibtexparser.load(fh)

    # Clean the entries if necessary
    bibtex.entries = [{k: entry[k]
                       for k in entry if k not in ignore_fields}
                      for entry in bibtex.entries]

    return bibtex