+the more interesting initial question is, "why no `pflis`?" and
+the answer to that is "because flis and fishmv do exactly the same
+job in exactly the same amount of bits" (64).
+`flis` fills in a BF16, `fishmv` extends to an FP32,
+and `pflis` would fill in an FP32 in exactly the same amount
+of space, making it a redundant encoding. this just leaves the
+purpose of `pfishmv` to be to extend (fill) an FP32 out to an FP64.
+