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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 sxform(instring, tostring, et):
 """ Return the state transformation matrix from one frame to another at a specified epoch. http://naif.jpl.nasa.gov/pub/naif/toolkit_docs/C/cspice/sxform_c.html :param instring: Name of the frame to transform from. :type instring: str :param tostring: Name of the frame to transform to. :type tostring: str :param et: Epoch of the state transformation matrix. :type et: Union[float,Iterable[float]] :return: A state transformation matrix. :rtype: 6x6-Element Array of floats """

    instring = stypes.stringToCharP(instring)
    tostring = stypes.stringToCharP(tostring)
    xform = stypes.emptyDoubleMatrix(x=6, y=6)
    if hasattr(et, "__iter__"):
        xforms = []
        for t in et:
            libspice.sxform_c(instring, tostring, ctypes.c_double(t), xform)
            checkForSpiceError(None)
            xforms.append(stypes.cMatrixToNumpy(xform))
        return xforms
    else:
        et = ctypes.c_double(et)
        libspice.sxform_c(instring, tostring, et, xform)
        return stypes.cMatrixToNumpy(xform)