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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 _afterpoint(string):
 """Symbols after a decimal point, -1 if the string lacks the decimal point. 2 -1 -1 2 """

    if _isnumber(string):
        if _isint(string):
            return -1
        else:
            pos = string.rfind(".")
            pos = string.lower().rfind("e") if pos < 0 else pos
            if pos >= 0:
                return len(string) - pos - 1
            else:
                return -1  # no point
    else:
        return -1