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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_instrinsic(input):
 """ Checks if the given input is an intrinsic function dictionary. Intrinsic function is a dictionary with single key that is the name of the intrinsics. :param input: Input value to check if it is an intrinsic :return: True, if yes """


    if input is not None \
            and isinstance(input, dict) \
            and len(input) == 1:

        key = list(input.keys())[0]
        return key == "Ref" or key == "Condition" or key.startswith("Fn::")

    return False