<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _safe_processing(nsafefn, source, _globals=None, _locals=None):
 """Do a safe processing of input fn in using SAFE_BUILTINS. :param fn: function to call with input parameters. :param source: source object to process with fn. :param dict _globals: global objects by name. :param dict _locals: local objects by name. :return: fn processing result"""


    if _globals is None:
        _globals = SAFE_BUILTINS

    else:
        _globals.update(SAFE_BUILTINS)

    return nsafefn(source, _globals, _locals)