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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_existance(f):
 """Check if the file supplied as input exists."""

    if not opath.isfile(f):
        logging.error("Nanoget: File provided doesn't exist or the path is incorrect: {}".format(f))
        sys.exit("File provided doesn't exist or the path is incorrect: {}".format(f))