Function builtin_starts_with 

fn builtin_starts_with(
    args: &[RValue],
    _: &[(String, RValue)],
) -> Result<RValue, RError>

Test whether strings start with a given prefix.

Vectorized over both x and prefix with recycling.

@param x character vector to test @param prefix character vector: the prefix(es) to look for @return logical vector indicating which elements start with the prefix