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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 truncate_too_long_number(numobj):
 """Truncate a number object that is too long. Attempts to extract a valid number from a phone number that is too long to be valid, and resets the PhoneNumber object passed in to that valid version. If no valid number could be extracted, the PhoneNumber object passed in will not be modified. Arguments: numobj -- A PhoneNumber object which contains a number that is too long to be valid. Returns True if a valid phone number can be successfully extracted. """

    if is_valid_number(numobj):
        return True
    numobj_copy = PhoneNumber()
    numobj_copy.merge_from(numobj)
    national_number = numobj.national_number

    while not is_valid_number(numobj_copy):
        # Strip a digit off the RHS
        national_number = national_number // 10
        numobj_copy.national_number = national_number
        validation_result = is_possible_number_with_reason(numobj_copy)
        if (validation_result == ValidationResult.TOO_SHORT or
            national_number == 0):
            return False
    # To reach here, numobj_copy is a valid number.  Modify the original object
    numobj.national_number = national_number
    return True