Function interp_filter 

fn interp_filter(
    positional: &[RValue],
    named: &[(String, RValue)],
    context: &BuiltinContext<'_>,
) -> Result<RValue, RError>

Select elements of a vector or list for which a predicate returns TRUE.

@param f predicate function returning a logical scalar @param x vector or list to filter @return elements of x for which f returns TRUE