implements PlotFile:
- Since we are now implementing PlotFiler we need to add implements PlotFile to the top of the class definition.
```
public class OrangeFile extends BaseFile implements PlotFile
```
The X-Axis:
- In Lab 1 we implemented getXStart() and getXDelta(), now we need to add getXUnits() and getXFrame().
- getXUnits() is looking for the units associated with the X-axis (PLOT uses this for the axis title). Since an ORANGE file does not have any units specified, we can just return Units.NONE.
- getXFrame() gives the frame size for a 2D file. In our case we have 1D data so the x-axis frame size is 1.

The Y-Axis:

Since we only have 1D data, there is no Y-axis to speak of. So we are just going to return the default values for everything.

  public double getYStart () { return 0.0; }
  public double getYDelta () { return 1.0; }
  public int    getYUnits () { return Units.NONE; }
  public int    getYFrame () { return 1;   }

The "Primary" Axis:

The "primary" axis is just the main axis. Most of the time this is the X-axis, except in the case of 2D data where the Y-axis is used.

  public double getStart () { return getXStart(); }
  public double getDelta () { return getXDelta(); }
  public int    getUnits () { return getXUnits(); }
  public int    getFrame () { return getXFrame(); }

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