.. efun:: int extern_call()

  Returns zero, if the function that is currently being executed was called by a local call, non-zero for :efun:`call_other`, driver applies, closure calls, etc. Currently the only return value for them is 1, but later the various methods may be distinguished by means of the return value.

  :history 3.2@263 introduced: resp. 3.2.1@12

  .. todo:: not clear what to do with the "resp..." above

  .. seealso:: :efun:`call_other`, :efun:`previous_object`