how loop a precomp in after effects

Un-PreCompose is a plug-in for After Effects that allows you to select a pre-comp (nested composition) and extract all of its layers into the parent composition while maintaining each layers effects and other properties. You are given various options for maintaining or deleting properties from the pre-comp and the pre- comp itself.
Using Un-PreCompose?
Using Un-PreCompose is simple. Once it is installed, it will show up at the bottom of the 'Layer' menu. If you do not have a pre-comp (nested composition) selected, Un-PreCompose will be greyed out and disabled. To use Un-PreCompose, just select a pre-comp in the timeline panel, then go to Layer>Un- PreCompose
Un-PreCompose Options
Un-PreComposed Layer Prefix
This option will help you see which layers came from the pre-comp. Whatever you put into this textbox will be added to the beginning of each layer that is un-precomposed. If no prefix is desired, just leave the box empty.
Copy Pre-Comp attributes to layers (Note on this option in the next section)
If you have key frames, effects, etc. applied to your pre-comp and want those attribute to be maintained, select this option. Each layer inside will then receive the effects from its parent and will be made a child of a null object that contains the transform attributes. The null object will have the name ||CONTROLLER||.
Discard Pre-Comp Attributes
This option will get rid of any attributes that are applied to your pre-comp. Layers inside the pre-comp will maintain their current positions and attributes. You may notice a change in position if your pre- comp is a different resolution then its parent composition.
Delete Source After Un-PreComposing
If this option is selected, once the pre-comp has been un-precomposed, it will be deleted from the project. This option will not be available if the pre-comp is being used elsewhere in the project. This option will be disabled if the 'Keep Pre-Comp in Composition' option is selected.
Keep Pre-Comp in Composition
If this option is selected, the pre-comp will remain in the parent composition after the Un-PreCompose has taken place. The pre-comp will be turned off, but still be a part of the composition. This option will be disabled if the 'Delete Source After Un-PreComposing' option is checked.
Notes on 'Copy Pre-Comp Attributes to Layers'
1) Masks are NOT copied
For the moment, masks applied to your pre-comp will not be copied over to the extracted layers. This may change in the future, so keep a look out for any updates to the plug-in
2) Particle Layers
If your pre-comp is a 3D layer that contains particle layers, you may get some issues on running the plug-in. Particle layers are usually meant to be applied to 2D layers, but if the parent comp is 3D, every layer inside will be changed to a 3D layer, so you might get some strange results.
3) Creation of Controller Layer
For now, the, any transform attributes of the pre-comp are applied to the null object, which then becomes the parent of each extracted layer. If a layer already has a parent, that layer will not be affected.
General Notes
1. Parenting is maintained within the pre-comp, however if any layers are parented to the pre-comp, that connection will be broken.
2. If layers inside your pre-comp contain expressions that use random numbers, you may notice a slight change due to random numbers being based on the layer's index, which may be changed when running an Un-PreCompose.

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