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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 open_file(filename, as_text=False):
 """Open the file gunzipping it if it ends with .gz. If as_text the file is opened in text mode, otherwise the file's opened in binary mode."""

    if filename.lower().endswith('.gz'):
        if as_text:
            return gzip.open(filename, 'rt')
        else:
            return gzip.open(filename, 'rb')
    else:
        if as_text:
            return open(filename, 'rt')
        else:
            return open(filename, 'rb')