locate_mandatory_LaTeX_argument: Locate contents of LaTeX commands
In TeXCheckR: Parses LaTeX Documents for Errors

Provides the locations of LaTeX commands with mandatory arguments.

locate_mandatory_LaTeX_argument(
  tex_lines,
  command_name,
  n = 1L,
  parsed_doc = NULL
)

`tex_lines`	A character vector of a LaTeX document, – for example as obtained from `readLines("mydoc.tex")`.
`command_name`	The command (without backslash) whose arguments' locations are desired.
`n`	Integer vector: which argument(s) to locate. If `n = NA`, the n-th argument positions for all n.
`parsed_doc`	The result of `parse_tex(tex_lines)`.