Display or return current debugging function stack information. With optional argument n, omit the n innermost stack frames.
The optional return argument stack is a struct array with the following fields:
- file
 - The name of the m-file where the function code is located.
 - name
 - The name of the function with a breakpoint.
 - line
 - The line number of an active breakpoint.
 - column
 - The column number of the line where the breakpoint begins.
 - scope
 - Undocumented.
 - context
 - Undocumented.
 The return argument idx specifies which element of the stack struct array is currently active.