Function interp_sys_unsetenv 

fn interp_sys_unsetenv(
    args: &[RValue],
    _named: &[(String, RValue)],
    context: &BuiltinContext<'_>,
) -> Result<RValue, RError>

Unset environment variables in the interpreter’s private environment.

@param x character vector of variable names to unset @return logical vector (TRUE for each successfully unset)