assertThat(inputStream.read()).isEqualTo('A'.code)
    assertThat(inputStream.read()).isEqualTo('B'.code)
    assertThat(inputStream.read()).isEqualTo('C'.code)
    assertThat(inputStream.read()).isEqualTo('D'.code)
    assertThat(inputStream.read()).isEqualTo('E'.code)
    assertThat(inputStream.read()).isEqualTo('F'.code)
    assertThat(inputStream.read()).isEqualTo(-1)

        You normally wouldn't use this from a file you read in a request.

        To be awaitable, compatible with async, this is run in threadpool.
        """
        return await super().write(data)

    async def read(
        self,
        size: Annotated[
            int,
            Doc(
                """
                The number of bytes to read from the file.
                """
            ),

			b = append(b, 0)[:len(b)]
		}
		n, err := r.Read(b[len(b):cap(b)])
		b = b[:len(b)+n]
		if err != nil {
			if errors.Is(err, io.EOF) {
				if want >= 0 && read+int64(n) != want {
					return nil, io.ErrUnexpectedEOF
				}
				err = nil
			}
			return b, err
		}
		read += int64(n)
		if want >= 0 && read == want {
			// No need to read more...
			return b, nil
		}
	}
}

// Use it with other programs, like
$ echo "Hello $Env:MY_NAME"

Hello Wade Wilson
```

</div>

////

## Read env vars in Python { #read-env-vars-in-python }

You could also create environment variables **outside** of Python, in the terminal (or with any other method), and then **read them in Python**.

For example you could have a file `main.py` with:

```Python hl_lines="3"
import os

    ByteSource source = out.asByteSource();

    out.write(data);
    assertThat(source.read()).isEqualTo(data);

    out.reset();
    assertThat(source.read()).isEmpty();

    out.write(data);
    assertThat(source.read()).isEqualTo(data);

    out.close();
  }

  private static boolean isAndroid() {

    ByteSource source = out.asByteSource();

    out.write(data);
    assertThat(source.read()).isEqualTo(data);

    out.reset();
    assertThat(source.read()).isEmpty();

    out.write(data);
    assertThat(source.read()).isEqualTo(data);

    out.close();
  }

  private static boolean isAndroid() {

	dst   chan [][]string // result of block decode
	err   error           // any error encountered will be set here
}

// Read - reads single record.
// Once Read is called the previous record should no longer be referenced.
func (r *Reader) Read(dst sql.Record) (sql.Record, error) {
	// If we have have any records left, return these before any error.
	for len(r.current) <= r.recordsRead {
		if r.err != nil {

    assertTrue(source.wasStreamOpened());
    assertFalse(source.wasStreamClosed());

    StringWriter writer = new StringWriter();
    char[] buf = new char[64];
    int read;
    while ((read = reader.read(buf)) != -1) {
      writer.write(buf, 0, read);
    }
    reader.close();
    writer.close();

    assertTrue(source.wasStreamClosed());
    assertEquals(STRING, writer.toString());
  }

    assertEquals(expected.charAt(0), joinedReader.read());
    CharStreams.skipFully(joinedReader, 1);
    assertEquals(expected.charAt(2), joinedReader.read());
    CharStreams.skipFully(joinedReader, 4);
    assertEquals(expected.charAt(7), joinedReader.read());
    CharStreams.skipFully(joinedReader, 1);
    assertEquals(expected.charAt(9), joinedReader.read());
    assertEquals(-1, joinedReader.read());
  }

		Method: Deflate,
		Mode:   0755 | fs.ModeDevice | fs.ModeCharDevice,
	},
}

func TestWriter(t *testing.T) {
	largeData := make([]byte, 1<<17)
	if _, err := rand.Read(largeData); err != nil {
		t.Fatal("rand.Read failed:", err)
	}
	writeTests[1].Data = largeData
	defer func() {
		writeTests[1].Data = nil
	}()

	// write a zip file
	buf := new(bytes.Buffer)
	w := NewWriter(buf)