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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 load_bnf_file(filepath, repository = None):
 """Converts a bnf file into a BNFGrammar instance"""

    linelist = []
    with open(filepath,'r') as mlfile:
        for line in mlfile:
            linelist.append(line)
    return strlist_to_production_set(linelist, repository)