Function isEString

isEString(string_: string): string_ is `E${number}`
Tests if a string is an EString. Can also be used as a type guard.
Parameters
- string_: string
  The string to test.
Returns string_ is `E${number}`
True if the string is an EString.
Example
```
const property = 'E123';
   if (!isEString(property)) {
       throw new Error('Not an EString');
   }
   EntitySchemaSnak.fromID('P698', property);
```
- Defined in utils/guards/strings.ts:78