that it must return a `NumericGrade` object, and the last step is to set the value of the grades for the first `NumericGrade` object sent to the function:

    setMethod("Ops", signature(e1="NumericGrade", e2="NumericGrade"),
        function(e1, e2) {
            theSum <- callGeneric(GetValue(e1), GetValue(e2))
            return(SetValue(e1,theSum))
        }
    )

    setMethod("Ops", signature(e1="NumericGrade", e2="numeric"),
        function(e1, e2) {
            theSum <- callGeneric(GetValue(e1), e2)
            return(SetValue(e1,theSum))
  120 years of hippocampal Schaffer collaterals.
Károly Schaffer (1864-1939) was a Hungarian neurologist who distinguished himself through original discoveries in human neuropathology. At the beginning of his scientific carrier, he described the cellular and fiber structure of the hippocampus, earning him a high reputation in neuroscience. Schaffer (1892) described the so-called "collateral fiber system" that connects the CA3 and CA1 regions of the hippocampus, known today as Schaffer collaterals. To decipher the history of this well-known eponym, we review Schaffer's original German publication and follow the impact of his research in the contemporary literature.