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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 is_text_extractor_available(extension: str) -> bool: """ Is a text extractor available for the specified extension? """

    if extension is not None:
        extension = extension.lower()
    info = ext_map.get(extension)
    if info is None:
        return False
    availability = info[AVAILABILITY]
    if type(availability) == bool:
        return availability
    elif callable(availability):
        return availability()
    else:
        raise ValueError(
            "Bad information object for extension: {}".format(extension))