pub trait SysBlocks {
// Required methods
fn read_dir(&self) -> ReadDir;
fn read_env(&self) -> ReadEnv;
fn read_file(&self) -> ReadFile;
fn read_stdin(&self) -> ReadStdin;
fn write_file(&self) -> WriteFile;
fn write_stderr(&self) -> WriteStderr;
fn write_stdout(&self) -> WriteStdout;
}