Function json_strip_nulls_argument_positions 

pub fn json_strip_nulls_argument_positions(
    name: &str,
    argument_names: &[Option<&str>],
) -> Result<Option<Vec<usize>>>

Map call-order arguments onto the declared (target, strip_in_arrays DEFAULT false) slots. None means the arity or a named argument does not select either catalogued overload.