intended use: error messages for the user
util_find_external_functions_in_stacktrace(
sfs = rev(sys.frames()),
cls = rev(sys.calls())
)vector of logicals stating for each index, if it had been called externally
reverse sys.frames to search in
reverse sys.calls to search in
Other condition_functions:
util_condition_constructor_factory(),
util_deparse1(),
util_error(),
util_find_first_externally_called_functions_in_stacktrace(),
util_find_indicator_function_in_callers(),
util_message(),
util_warning()