operator: to-coeff

    description:
        to-coeff ket
        replace the ket text with ' '
        ie, only keep the coefficient

    examples:
        -- if the ket is the don't know ket, return the don't know ket:
        to-coeff 12|>
            |>
        
        to-coeff 26|a: b>
            26| >

        -- since the ket text is now the same, the coefficients add up:
        to-coeff (26|a: b> + 13|x>)
            39| >

        -- another longer example:
        to-coeff (3|a: b: c> + 5|x: y> + 7|fish> + 2.5|animal: mammal: cat>)
            17.5| >

    see also:


Home