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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 get_guest_property_value(self, property_p):
 """Reads a value from the machine's guest property store. in property_p of type str The name of the property to read. return value of type str The value of the property. If the property does not exist then this will be empty. raises :class:`VBoxErrorInvalidVmState` Machine session is not open. """

        if not isinstance(property_p, basestring):
            raise TypeError("property_p can only be an instance of type basestring")
        value = self._call("getGuestPropertyValue",
                     in_p=[property_p])
        return value