This function returns a description of the call stack at this moment.
The description is returned in an array with one entry for each call
in the stack. Each entry has this format:
({
- file,
- /* a string with the filename if known, else zero */
- function,
- /* The function-pointer to the called function */
- line,
- /* an integer containing the line if known, else zero */
})
The current call frame will be last in the array, and the one above
that the last but one and so on.