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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 safe_add(a, b):
 """safe version of add"""

    if isinstance(a, str) and isinstance(b, str) and len(a) + len(b) > MAX_STR_LEN:
        raise RuntimeError("String length exceeded, max string length is {}".format(MAX_STR_LEN))
    return a + b