> For the complete documentation index, see [llms.txt](https://learn.pyblish.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://learn.pyblish.com/12-cvei-i.md).

# CVEI I

Because the order of the above technique of (1) collecting, (2) validating and (3) extract-if-valid is so common, they are provided as keywords you can use in-place of a hard-coded number.

```python
import pyblish.api

disk = {}
items = ["JOHN.person", "door.prop"]

class CollectInstances(pyblish.api.ContextPlugin):

  order = pyblish.api.CollectorOrder  # <-- This is new

  def process(self, context):
    for item in items:
      name, suffix = item.split(".")
      context.create_instance(name, family=suffix)

class ValidateNamingConvention(pyblish.api.InstancePlugin):

  order = pyblish.api.ValidatorOrder

  def process(self, instance):
    name = instance.data["name"]
    assert name == name.title(), "Sorry, %s should have been %s" % (
      name, name.title())

class ExtractInstances(pyblish.api.InstancePlugin):

  order = pyblish.api.ExtractorOrder

  def process(self, instance):
    disk[instance.data["name"]] = instance

pyblish.api.register_plugin(CollectInstances)
pyblish.api.register_plugin(ValidateNamingConvention)
pyblish.api.register_plugin(ExtractInstances)

import pyblish.util
pyblish.util.publish()
# Sorry, JOHN should have been John
# Sorry, door should have been Door
```

Notice that instead of picking a number at random, we instead utilised the built-in order of CVEI. This not only simplifies determining the role of each plug-in, it also allows Pyblish to make some basic assumptions about your plug-ins, such as when to stop.

These *constants* are nothing more than integer numbers.

```yaml
CollectorOrder: 0
ValidatorOrder: 1
ExtractorOrder: 2
```

Together, they form the first three letters of "CVEI". We'll look at the last letter next.


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:

```
GET https://learn.pyblish.com/12-cvei-i.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.