<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def get(self, opttype, strike, expiry):
 """ Price as midpoint between bid and ask. Parameters opttype : str 'call' or 'put'. strike : numeric Strike price. expiry : date-like Expiration date. Can be a :class:`datetime.datetime` or a string that :mod:`pandas` can interpret as such, e.g. '2015-01-01'. Returns ------- out : float Examples -------- 0.94 """

        _optrow = _relevant_rows(self.data, (strike, expiry, opttype,),
                "No key for {} strike {} {}".format(expiry, strike, opttype))
        return _getprice(_optrow)