cmd_file_expect: Creates list of paths by file extension & checks they exist
In snystrom/dotargs: Framework for Building Interfaces to Shell Commands

Description Usage Arguments Details Value Examples

Ext or prefix can be a vector or single character. The shorter value will be propagated across all values of the other. See Examples for details.

1	cmd_file_expect(prefix, ext, outdir = ".")

`prefix`	name of file prefix for each extension.
`ext`	vector of file extensions
`outdir`	directory the files will be inside

If files are not found, throws an error

vector of valid file paths

## Not run: 
# Expects many file types of same prefix
# ie myFile.txt, myFile.html, myFile.xml
cmd_file_expect("myFile", c("txt", "html", "xml"))

# Expects many files of same type
# ie myFile1.txt, myFile2.txt, myFile3.txt
cmd_file_expect(c("myFile1", "myFile2", "myFile3"), "txt")

# Expects many files with each prefix and each extension
# ie myFile1.txt, myFile1.html, myFile2.txt, myFile2.html
cmd_file_expect(c("myFile1", "myFile2"), c("txt", "html"))


## End(Not run)