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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_single(parser, filepath):
 """Reads a single config file into the parser, silently failing if the file does not exist. Args: parser (ConfigParser):
 parser to read the file into. filepath (str):
 full path to the config file. """

    from os import path
    global packages
    if path.isfile(filepath):
        parser.readfp(open(filepath))