Gets an array of the function's argument list.
This function may be used in conjunction with func_get_arg() and func_num_args() to allow user-defined functions to accept variable-length argument lists.
Returns an array in which each element is a copy of the corresponding member of the current user-defined function's argument list.
Note: Because this function depends on the current scope to determine parameter details, it cannot be used as a function parameter. If you must pass this value, assign the results to a variable, and pass the variable.
Note: This function returns a copy of the passed arguments only, and does not account for default (non-passed) arguments.