Cannot set a value to non-existent attribute within a field

Hi,
I have this issue. I am trying to fill forms of this website using robobrowser. My code in python is below:
```
new_CRTS_DR3_beta_url = 'http://crts.iucaa.in/CRTS/'
browser = RoboBrowser()
browser.open(new_CRTS_DR3_beta_url)
form = browser.get_form(action='/CRTS/imaging')
form['query_input'].value = '332.64277 -22.66323'
form['radius'].value = '0.1'
```
However, 'query_input' does not have the attribute value before I fill the input, and when the input is filled the attribute value appears and is set with the input value. The HTML code looks like:
- Before when it is empty:
```

```
- After setting an input:
```

```
Thank you for any help!

Start by reproducing the reported form assignment with the RoboBrowser snippet and the referenced /CRTS/imaging form. Trace how form fields handle a missing value attribute, then verify the chosen behavior with a focused regression test; done means assigning query_input.value works consistently for this hidden input.

Written by the indexing model from the issue text.