Show all package functions that are called from a given function

Create a DiagrammeR graph that contains nodes of the type function and edges that have the relationship called_in.

function_graph_single(pkgattrs_tbl, target_fn, pkg_name = NULL)

Arguments

pkgattrs_tbl	A tibble object that contains package function information. This is created by the pkgattrs() function.
target_fn	the name of the function that is to be examined for its calls of package functions.
pkg_name	An optional package name for filtering the tibble provided to pkgattrs_tbl, which is useful if that tibble describes multiple packages.