Script to copy javascript files and append ".flow" to the filename.
npm install flow-copy-source   
This is a simple script which finds all .js, .jsx, and .mjs files in one or
more source directories, and copies them into a destination directory with the
.flow suffix appended to the filename.
This is intended to be used as a build step for Flow-typed Javascript projects
so that the original typed source files can be placed in the same directory as
the transpiled code, so that Flow can use the type definitions in the original
source code.
``
Usage: bin/flow-copy-source.js [-v|--verbose] [-w|--watch] [-i PATTERN]... SRC... DEST
Options:
-v, --verbose Show changes [boolean]
-w, --watch Re-copy files on change [boolean]
-i, --ignore ignore pattern (glob expression)
`
Multiple --ignore patterns may be given by using the --ignore option
multiple times.
This module also exports the flowCopySource(sources, dest, options) function.sources must be an array of strings, dest must be a string, and options
may optionally be an object with optional and watch boolean{src, dest}`
properties. The function returns a promise for an array of
objects listing the operations done.