Inputs to files nested within LaTeX document
inputs_of(filename, exclude.preamble = TRUE, append.tex = TRUE)A character vector of file paths relative to filename that are
used as \inputs or \includes within filename. If
no such files are present within filename, NULL is returned.
The file whose \inputs are to be extracted.
(logical) If TRUE, the default, only \inputs and \includes within the document environment are returned.
Should the result include the file extension .tex? By default, TRUE. Setting to FALSE may be useful when the file is not a .tex file.