Function getPubchemIdFromDocument

getPubchemIdFromDocument(doc: Document): undefined | number
Gets the PubChem ID from the links in the document.
Parameters
- doc: Document
  The document to search for PubChem links
Returns undefined | number
The PubChem ID, or undefined if not found
Example
```
const pubchemId = getPubchemIdFromDocument(document);
console.log(pubchemId);
// Outputs: 1234567890
```
- Defined in src/helpers/pubchem.ts:849