Add decorator for build.hook('build').

[wesselvdv]

I am using the build.hook('build') to change the BigFloat to Float, but I can't use the same pattern as for the rest. Which is a shame, any chance it could be added?

[alex-ald]

@wesselvdv Hey, sorry for the late reply! I'll definitely look into this to see if this can be added, but I am really busy at the moment so this might take a bit.