def _get_registerd_func(name_or_func):
<EOL>if callable(name_or_func):<EOL><INDENT>func = register_array_xcorr(name_or_func)<EOL><DEDENT>else:<EOL><INDENT>func = XCOR_FUNCS[name_or_func or '<STR_LIT:default>']<EOL><DEDENT>assert callable(func), '<STR_LIT>'<EOL>if not hasattr(func, '<STR_LIT>'):<EOL><INDENT>func = register_array_xcorr(func)<EOL><DEDENT>return func<EOL>
get a xcorr function from a str or callable.